The Practical Guide To Consulting Interviews

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C o n te n ts Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Chapter 1: 100 Practical Interview Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 General tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Behavioral tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 “Fit” tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Case studies tips - Starting on the right foot . . . . . . . . . . . . . . . . . . . . . . . . 28 Case studies tips - Structuring your case . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Case studies tips - Cracking the case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Case studies tips - Acing quant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Case studies tips - Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Q/A and closure tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Post interviews tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Chapter 2: Most Common Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Chapter 3: Market Sizing Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Intro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Case study 1 – How many people are working out right now? . . . . . . . . . . 76 Case study 2 – How many planes are currently in the air? . . . . . . . . . . . . . 85 Case study 3 – How many bottles of water are sold each year? . . . . . . . . . . 92 Case study 4 – How many people wear jackets on a typical Monday in the

UAE? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Chapter 4 – Profitability Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Intro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 Case study 5 – Does it make sense to open a hotdog stand in

my hometown? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 2

Case study 6 – How much does a barber make in Paris? . . . . . . . . . . . . . . 124 Case study 7 – Data center in London . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Case study 8 – Famous retailer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Case study 9 – Stop the bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Chapter 5 – Merger & Acquisition Case Studies . . . . . . . . . . . . . . . . . . . . 155 Intro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Case study 10 – Acquiring a theme park . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Chapter 6 – Pricing Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Intro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 Case study 11 – The meal pill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

Case study 12 – The cancer pill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 One Last Thing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

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I ntr o d u c t io n Your practical way into consulting  Cracking consulting interviews is not about memorizing thousands of

frameworks and practicing a million case studies. It is about following a

series of intuitive tips and guidelines. Now, of course, you need to know the basics, but these are easy to learn.

More is less, and if you fall into the trap of memorizing how to crack the

interviews (e.g., “I should always do this when asked that”), you won’t come

across as naturally confident, creative, and spontaneous as interviewers would want you to be.

I have always been a practical person, always looking for pragmatic ways

to crack academics, corporate interviews, financial investments, and more. As a former MBB consultant, I was taught the Pareto Principle (i.e., the

80/20 rule) in my first job, and I now apply it in various situations, whether professional or personal.

What is the 80/20 rule? The rule states that 80% of consequences (or

performance) result from 20% of causes (or preparation). This means that

only a few yet important actions yield most of the results. Let me explain: Pareto first observed that 80% of the land in Italy was owned by 20% of

the population. He then conducted a series of surveys to realize that the

distribution is quite similar in many other countries. The principle was then expanded to span hundreds of industries and situations. The examples are

countless: Microsoft noted that 80% of computing errors could be eliminated by fixing 20% of the most-reported bugs; 20% of criminals commit 80% of 4

crimes; 20% of drivers cause 80% of road accidents; 20% of factories cause 80% of the pollution. You get the point.

Through this book, I’m aiming to add one more example to the mix by

offering you 20% of what you need to know about consulting interview

preparations for you to ace 80% of your interviews without overwhelming yourselves with details that barely move the needle. You will never be able

to practice every single case study, do mock interviews with every consultant you know or attend every consulting prep workshop out there, but you don’t really need to.

Consulting interview structure Before we go into practical tips, it’s important for you to know how most management consulting interviews are structured. Although interview

formats differ from one company to the other, most of them involve three key segments: the “fit” part, the case study, and the Q&A. 

Part 1: The “fit” segment is the part in which you are asked to answer a series of quick questions or occasionally tell fewer but longer stories of yourself.

The former is the most common format. However, some companies, such as

McKinsey, tend to favor the latter approach. For instance, during a McKinsey interview, you might be asked to discuss for 10 minutes a time you showed leadership skills, teamwork skills or other key skills.

In this book, we’ll help you ace the fit part of the interview, irrespective of its format.

Part 2: The bulk of the preparation usually goes into the case study section. It’s what a lot of candidates fear, as case studies might sound difficult and intimidating at first.

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A business case study is a fictitious business issue or question that the

interviewer puts forward for you to crack. It could be about a business that’s about to launch, a company that is bleeding money, a market that needs to

be sized, etc. With the help of this book, we’ll ensure you get exposed to the most common types of cases and that you’re properly equipped to navigate any case you’re given. Since we’re all about practicalities, we’ll also delve deeper into several real-life case examples to train you.

Part 3: The Q/A segment usually lasts just a few minutes. You will often be given a chance to ask the interviewer questions, and believe it or not, the

questions you ask, how you ask them, and how you maintain the conversation all affect your overall interview performance. Why this book? I’ve personally read dozens of books about consulting interviews, listened

to webinars, attended workshops and enrolled in private lessons. However, it was only through practical tips and real-life guidance that I was able to

comfortably step into interviews. The bad news is that these tips have never

been fully consolidated for candidates to access. The good news is that we’re doing that in this book.

I have already supported hundreds of individuals in securing their consulting jobs. In an attempt to consolidate the key aspects and tips, I’m writing this book, hoping to pass them on to any student or employee looking to crack his or her way into consulting without going through the typical hassle. One last thing: It’s subjective! The purpose of this book is to shed some light on key processes and tips that might help you in your interviews. It is not intended to be an academic 6

reference. You might agree or disagree with the concepts, assumptions,

and calculations we’ll be making throughout, but that’s okay. How to act in interviews, how to crack case studies, which questions to ask, how to communicate—these are all subjective.

You might find that the way we went about sizing a certain market is not

perfect. In that case, we couldn’t be more proud of the person you developed into as you read that book. In reality, you will need to come up with your own way of acing interviews; we will only be providing you with strong

fundamentals to do so. Take what is helpful, drop what is not, and let’s have fun throughout!

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Chapter One

100 Practical Interview Tips

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g e ne r a l ti p s As you start to prepare for your interviews, there are general tips to keep in mind. These are not tactical dos and don’ts for case studies or even for the fit part. They are broader principles that you can follow throughout your preparations.

Tip 1 – Theory is good; practice is king There are hundreds of books and sources out there to help you prepare for consulting interviews. Plan to read and digest them all, and you’ll quickly get overwhelmed. The secret to cracking interviews lies in understanding the basics and spending most of your time practicing, ideally with peers, consultants, ex-consultants or even in actual interviews (yes, formal

interviews train you the most, as it’s only then that you’ll be 100% immersed in the interview experience).

The cases you solve and the questions you answer correctly reassure you

of what you know. It is, however, the questions you don’t get right and the mistakes you make that prepare you the most. The more you practice, the

more gaps you’ll fill as you prepare for the real interviews, whether it’s math

shortcuts you take, frameworks you use or more. So yeah, theory is good and important, but practice is what will get you to the finish line. Tip 2 – Don’t be a lone wolf Some of us have a tendency to prepare for interviews alone. It could be

because of one’s character or because we don’t want to burden peers with our

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preps or even because we feel it’s a

competitive process that is best dealt with individually. No matter what

the reason is, being a lone wolf is the

worst approach to cracking consulting interviews.

Although we have easy access to a variety of resources these days, it’s

still important to practice with peers

and tutors because only then will you be putting yourself in a real interview

setting. Having someone play the role of the interviewer is crucial, as it trains you to adapt to various new situations and gives you a human element you will never find in books (e.g., the interviewer can pressure you to answer

quickly, they can go off script to adapt to your answers and challenge you). Find yourself peers at school, at university, at work or on online platforms (there are a bunch of them now, google it). You can even find interview

buddies who are also applying for consulting jobs. That’s ideal as you would

train them and they would train you. With practice, you will spot each other’s development areas and ensure they are tested in your mock interviews. Tip 3 – Success doesn’t happen overnight Cracking consulting interviews can’t be done overnight. It requires time. Again, it’s a practice game, and it’s by making mistakes and by getting

exposed to new situations that you will train yourself. How much time

does it take? Well, it really depends on a wide set of factors, such as your business background, how comfortable you are in formal settings, your

communication skills, the hours you’re putting in, and more. In general, I’ve seen people who prepared for a few days land an offer, and I’ve seen people who prepared for two whole months and not land one. It’s not a matter of

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how much time you spend preparing but a matter of whether you’re prepping well. Read this book and a few other sources, practice as much as possible, and you should be fine.

Tip 4 – You will never be fully ready Take your average consultant today and put him/her in a consulting

interview. The chances of them succeeding are far below 100%. There will

always be things you don’t know, cases you’re more comfortable with than others, interviewers you’ll click with more than others, etc.

Don’t focus on learning it all and covering every single framework and

scenario out there. Focus on learning the 20% of things that will ensure you succeed at least 80% of the time. It’s a volume play, and one day, the stars

will align, and you will enter an interview in which you will click with the

interviewer and will be given a case study you’re comfortable cracking. When this happens, you’ll know you got it long before you get the official HR call. Tip 5 – Pace it As you prepare for interviews, don’t kill yourself. Give yourself enough sleep, practice cases moderately, and don’t

impair your mental health along the

way. Excessive practice might burn you

out, especially if the formal interview is

in a few days. It’s only through organic and consistent preparation that you will maximize the chances of grasping the concepts and memorizing the learnings.

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Try giving yourself enough sleep (around 8 hours a day) throughout the

preparation period, as it increases the chances of storing the various concepts you’re learning. Ideally, you can ask the people around you to also give you

the time and space you need to prepare well—limit personal and professional problems that might distract you—so that you’re fully focused. Do, however,

carry on with your day-to-day life; go out, have dinner with friends, watch

movies, work out, etc., as you also need a way to distress. The closer you get to the interview, the less you should focus on learning new concepts and

the more you should try to rest and relax to ensure you’re as energized and comfortable as possible on the day of the interview. Tip 6 – Understand the patterns As you go through preparations and real-life interviews, you’ll notice certain patterns in the types of questions asked, the types of case studies given,

the types of interviewers, and, more importantly, what you’re good at, and the areas that you need to improve on. Keep track of those and focus on

improving your weak spots (e.g., focus on the types of cases you don’t do so

well) as you gear up toward the next interview.

It’s a pattern game, so with practice, you’ll be able to adjust your strategy

depending on the interviewer you meet, the case you’re asked to solve, and the questions you are asked.

Tip 7 – Don’t miss the pre-drinks Many companies offer you a chance to meet their employees (and sometimes the actual interviewers) before the official interview. This could be through

coffee chats, book fairs, and other settings. I encourage you to attend those,

as these might be framed as casual and non-evaluative, but in reality, making a good impression there will make you stand out. For those of you who

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don’t know, it’s common practice for companies to bring together all the

interviewers at the end of each recruiting process for them to decide together which candidates will move to the next stage and which will not. The more allies you build, the more chances you have of gaining their votes. Tip 8 – Know your audience As you prepare for interviews, research the company you’re

applying to. Learn about their

mission, culture, and values. Visit their website to see if you can

gather any preparation materials.

Talk to people who work there to

find out what resonates during the interviews. Showing the interviewers you

relate to their culture is a sign of commitment and dedication to joining their company.

It’s also important to research the interviewer before you meet him or her. What is their background? How long have they been with the company?

What do they specialize in? What do they look for in a candidate? Talk to

the staff and conduct your own research to maximize your chances of making a good impression. However, this does not imply that you should artificially alter who you are to suit the interviewer’s preferences. Keep a healthy

balance between connecting with them and being yourself. You can easily

find information about them on LinkedIn or sometimes on the company’s website.

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Tip 9 – Your resume is your first written assignment The first written assignment an interviewer will review is your resume. It

gives an indication of whether you’re structured and whether you know how to synthesize your personal achievements and stories. If you can’t structure your own resume, how can they guarantee you’ll be able to structure client presentations and frameworks if hired?

Keep the formatting clean, the structure solid, and the language strong. Be concise and focus on highlighting the key skills they look for (leadership,

teamwork, innovation, etc.). Do not limit the bullets to what you’ve done but talk about the impact you’ve made. There’s obviously a lot to talk about when it comes to resumes, and there are a lot of resources online to help you shape yours. I just wanted to emphasize how crucial it is to write it well. Tip 10 – Have fun! My favorite tip: Don’t sweat it and have fun! It’s not rocket science, and you

WILL crack it once you give it the right effort and time. You didn’t get it the first time? So what? You will have plenty of other opportunities, so sit tight and enjoy the ride 🙂

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b e hav i o r a l ti p s Are we now diving into case studies and how to crack them? Well, not so

fast. You can be the god of case studies but fail to show you’re a person they would want to work with, and you’re out. Let’s talk a bit about practical behavioral tips you need to know as you prepare for your interviews. Tip 11 – First minute, first impression Whether we like it or not, the first minute of the interview matters a lot.

The way you walk into the room, your handshake, your eye contact. All of

these will implicitly affect the way you are perceived. Walk confidently, shake hands firmly (but don’t overdo it) and take a seat as if you’re about to have a meeting, not as if you’re sitting for a math exam—without showing signs of fear, stress or insecurity.

Tip 12 – Within 5 minutes, you can tell I’ve heard many interviewers, especially senior ones, say that within the first

5 minutes, they could tell whether it was a go or a no-go. I can relate to that as a current interviewer. Everything you look for in a candidate, be it clean

communication, structured thinking, interesting stories, strong character, etc., will surface in the first few minutes of the interview. The rest of the session

is purely to validate whether that first impression was accurate or not. Focus on these first few minutes and sell yourself from the get-go (e.g., mention

interesting facts in the first chit-chat, show you’re approachable, and make them love your character before they assess your technical skills).

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Tip 13 – It’s a sales pitch Throughout the interview, make sure you mention directly or indirectly the things that make you stand out. At the end of the day, the goal is to sell

yourself and convince the interviewers that you, among all others, should be hired. You should know which interesting facts to release when (e.g., in the

personal questions part of the interview, in the Q&A or even during the case part if it’s relevant). Do not go with the flow by just answering the questions briefly, solving the case, and leaving; there’s nothing interesting about that. Being passive and reactive might not give you windows to release some of

your interesting facts, so create that opportunity and steer the discussion to cover topics that are compatible with your strengths and achievements. Tip 14 – Be confident, it’s sexy This is a recurring theme, but I can’t stress how important confidence is.

When the interviewers look at you, they’re wondering whether they would be comfortable putting you in front of their own clients. They’re looking for mature individuals who can elevate the company’s image. That said,

showcasing confidence and maturity gets you a step closer to being accepted into the firm. You can do that by being assertive in your answers and by maintaining a strong presence throughout.

This applies to all candidates, but it’s particularly important for fresh grads who might portray a younger and/or inexperienced attitude. Counter that

with confidence, and you’ll be fine. At 22, I was already presenting perfectly

to C-Levels. Did they know my age? Probably not. Did they care? Nah. As long as you deliver outstanding results and you’re trustworthy, no one will question your background or age.

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Tip 15 – Smile; they’ll smile back There is a thin line between confidence and arrogance, and no one is a fan of the latter. The more serious you are,

the more serious your interviewer will

be. Don’t get me wrong; it’s still a formal setup, and you need to behave as

such. You can, however, maintain a friendly attitude (with a few smiles here and there), as it shows you’re approachable and it builds a rapport with the interviewer.

Numerous studies have shown that smiling at people causes them to smile back. That’s because a part of your brain, called the cingulate cortex, which

is responsible for unconscious responses, will cause you to mirror someone’s facial expressions. So yeah, smiles are contagious, after all, and a smiling interviewer can’t be a bad thing.

Tip 16 – It’s not an interview; it’s a conversation Keep in mind that you’re not taking an exam; you’re just having a normal

conversation with someone representing the company you want to work for.

Treat it as such, keep the conversation flowing, and don’t limit your responses to short and academic answers. Walk them through your thinking, get their feedback, and discuss what works and what doesn’t.

Don’t underestimate how much YOU can influence the course of the

interview. If you’re engaged and you’re entertaining a good discussion, the interviewer might open up more, which will, in turn, give you more room to discuss your stories and leave a lasting impression. You can apply the

same logic to case studies: The shorter your answers are, the less room you’re 18

giving the interviewer to understand your logic and to correct you along the way. Enjoy the conversation; you’re not in court, although he/she might be judging you sometimes.

Tip 17 – Stay calm; they will stress-interview you Some interviewers might put you in awkward situations by keeping a poker face throughout the session or by bombarding you with tricky questions

(e.g., what other revenue stream can you think of ? Ok… what else? What

else?) or by taking you out of your comfort zone (e.g., asking you to present

it on the whiteboard). Keep in mind that these might be what we call “stress interviews,” in which interviewers monitor the way you operate in stressful

circumstances. Consulting is an intense industry, and maintaining your cool

in such situations is critical. Stay confident, answer the questions and ask for time to think if you need it.

Tip 18 – What isn’t said might say the most Body language is the set of non-verbal

signals you use to communicate feelings and intentions. It plays a big role in

portraying a good image when talking

to people, especially in formal settings. During interviews, it’s not just what

you say that matters but also how you

say it and how your body language supports it. Since we’re all about practical tips, here are some of the top ones I gathered, but the list is nowhere near comprehensive. •

Sit properly on the chair and do not show signs of boredom. This will

show that you’re engaged in the discussion and that you really care about 19

landing that job. If you’re not interested in the discussion, chances are

you won’t last long on the job, and no one is looking for quitters to join their company. •

Keep both of your feet on the ground and avoid crossing your legs at

the knees, which can seem defensive or placing an ankle over one knee, which can seem overly casual.

•

Nod your head to show you’re following, but don’t do it excessively, as

•

Use subtle hand gestures to make your point, but not too frequently.

you might come off as artificial.

These gestures can guide the interviewer to follow and can give you a nice rhythm. However, overdoing it might cause distraction and discomfort for the person you’re talking to.

•

If you lose the attention of your interviewer, pause a bit, then gain back

•

You can fold your hands over each other in a resting position, as it shows

eye contact before proceeding.

you’re comfortable and confident.

Controlling your body language not only helps you avoid communicating

the wrong intentions but also helps you purposely convey the perception you want the interviewer to get. Be conscious of the dos and don’ts and apply them carefully in interviews.

Tip 19 – Dress for the occasion Understand the dress code beforehand and dress

accordingly. Typically, the dress code for consulting interviews is formal. For men, this usually entails a

suit jacket and slacks with a shirt and tie or a sweater and button-down. For women, a blouse and dress 20

pants or a statement dress might also work. Do not, however, crash into the room wearing a $10,000 suit. It’s an interview, not a wedding. Tip 20 – BYOE Bring Your Own Equipment. You’ll need a pen, paper, and your resume for the interview. Typically, the company provides that, but there are no

guarantees. Bring your own equipment. If they end up having their own

ready, the interviewer would still appreciate the fact that you came prepared.

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“f i t” ti p s The “fit” part of the interview is when the interviewer asks you personal

questions about your experience, your drive to join the company, impactful

stories about you and more. It’s basically to assess you as an individual before going into the case part, which is more technical.

Here’s a series of tips to keep in mind as you prepare for the fit part. You

might think it’s as simple as going in and talking about yourself, but it’s a

competitive process and it’s usually the most impressive candidates who end up landing the job.

Tip 21 – Know your stories, don’t memorize them As you prepare for the interview, take a moment and reflect back on the

key inspirational stories you’ve experienced. It’s important that these stories showcase key skills interviewers look for, such as leadership, teamwork,

innovation, and impact. You don’t need to have 30 stories. We recommend

having 3-5 stories you know well and that are diverse enough to be tweaked

to answer a variety of questions around strengths, weaknesses, and more. Do not memorize the stories word by word, but focus on the key highlights and

lowlights of each so that you’re able to tailor your answer as needed based on the interviewer’s question.

Interviewers are experienced and will be able to tell whether you’re natural or you’re just telling a story you memorized. That’s why it’s important to

remember only the key pointers and to let spontaneity govern during the

interview. You might not need to tell the full story if only part of it is relevant to the question, and you might want to come up with your own appropriate phrasing during the interview to tell it. 22

Tip 22 – Prove you’re a future leader One key skill interviewers look

for in your answers is leadership.

Are you the type of profile who can eventually go up the ladder and start leading teams or even represent the company? With

performance reviews happening

every 6-12 months and with hundreds of talent joining or leaving every year, the consulting “up or out” mentality ensures talent either get promoted or

leave. The more senior you get, the more you’re assessed on not just technical knowledge but character as well. That’s because, as a senior, you are expected to spend more client-facing time (leading projects, pitching proposals, etc.). If you show early signs of strong leadership skills, you’re maximizing your

chances of getting selected, as interviewers will feel you’re more of an “up”

than an “out.” Try to prove through your answers and past experiences that you fit the profile. This can be done by talking about experience in leading

teams directly (e.g., sports teams) or indirectly (e.g., group projects). It can

also be done by showcasing the impact you’ve left on people around you and how you affected the course of their lives (e.g., career coaching, tutoring, volunteering).

Tip 23 – Show you’re a team player Another skill interviewers look for is teamwork. In consulting, you’ll be

working in teams most of the time; you’ll often need to work with others

to compare insights, marry your workstream to theirs, and even coach new joiners. As a manager and up-to-partner, teamwork becomes even more

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important as you’re asked to lead bigger projects and manage multiple consultants with different workstreams.

Showing you’ve successfully worked in teams before and that you’re not someone who can only trust his or her own judgment sets you up for

success in consulting interviews. This can be done by mentioning previous

experiences of teamwork, whether in professional or personal settings (e.g., a previous work team, a university project team or even a sports/hobby

team). Make sure you mention the type of team player you are and what

you bring to the table. Some contribute by bringing in data/insights, some

by tracking tasks and timelines, some by challenging findings and others by

communicating them to the final audience. None is better than the other, but

giving the interviewer a flavor of the way you contribute makes your story more solid and interesting.

Tip 24 – “Why” is as important as “What” When telling the interviewer about your past experience, don’t focus purely

on the “what” (e.g., what you did, what project you were part of, what awards you won) but also focus on the “why” (e.g., why did you venture into this

project? What drove you to take such action?) This adds an interesting flavor to the discussion, as it makes your answers more meaningful, and it makes

the interviewer relate to the core rather than the superficial part of the story only.

Tip 25 – Show you’ve left a mark The reason you did something and the way you did it are important elements of a story, and so is the impact you have left behind. Doing a strategy is one thing, but improving the company’s profit margin by 3x because of

that strategy is another. Always mention the impact you made, not just the 24

actions you took. Whether it’s a personal, academic or professional story, the consequences of your initiatives are the most interesting part of the conversation.

This applies to interviews but also to your resume. Some candidates are

hardworking and might, as consultants, end up doing a lot of analysis and

preparing slides by putting in long hours. However, if that work doesn’t yield tangible results (e.g., insights are derived, core client problems are solved),

it won’t pay off. Show you’ve had a track record of delivering impact and quantify it when possible (e.g., you coached ten candidates, and seven of them passed their exam).

Tip 26 – Stay humble. No one likes a showoff As you showcase the various achievements you’ve had, stay humble and avoid sounding arrogant. This can be accomplished by consistently acknowledging

the contributions of other people in your stories and how they helped you get to where you are today. It can also be done by maintaining a humble tone of voice and by focusing on the “we” rather than on the “I” in the stories. Tip 27 – Don’t recap your resume; they have it In most interviews, the interviewer will be referring to your resume when asking you “fit” questions. Typically, they also take a quick look at your

resume before you even enter the room. This means that they know the key points in it and that you don’t need to re-summarize it for them. Focus on

spinning your stories using new words and angles; don’t tell them what they already know.

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What usually helps is keeping some interesting stories or experiences out of

your written resume so that you can use those as “cherries on top” if needed. Don’t put all your eggs in one basket.

Tip 28 – Don’t lie, but maybe sugarcoat Some people have more interesting stories than others. So you’re probably

wondering, “Is it fine to make stories up?” You’ll get a lot of opinions on this, but in my personal experience, making up stories will only get you so far.

Contradicting yourself in follow-up questions (e.g., saying it was a group

of 5 people then saying it’s actually 4) or in following interviews within the same company might expose you. Also, you will never be able to fake your excitement to keep the story flowing smoothly if what you’re saying isn’t

largely based on a true story (unless you’re a professional actor, in which case I would urge you to reconsider consulting as a career 🙂). My advice is: We

all have interesting stories to tell; it’s just a matter of spinning them the right way. Focus on the interesting parts, downplay the boring parts, and inflate the achievements, but do not lie. Tip 29 – Make it emotional As you tell your stories, ensure you pause on

emotional moments (e.g., a friend you made in

the process, something you lost, something you

celebrated). Again, we’re all human, and triggering your own emotions, as well as the interviewer’s,

will break the ice even more and will set the stage for a smoother interview. Plus, nothing sticks more than an emotional story.

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Tip 30 – New interview, new story When interviewing for a role, avoid repeating the same story to different interviewers. It’s highly likely that interviewers may reconvene to discuss your case, and you don’t want them to realize that you only have few

experiences that you’re recycling across. I would recommend keeping 4-5 stories in mind that are different enough yet can still tick the same boxes

if needed (e.g., showing leadership, teamwork, innovation). Change stories when changing interviewers whenever you can, unless you’re stuck. Now,

obviously, this tip applies to different interviews for the same company. It’s

totally fine to reuse stories when interviewing for a different company.

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S ta r ti ng o n th e right foot CASE STUDIES TIPS The case study part is one of the most important elements of a consulting interview. Regardless of whether it’s the most effective, it is still the most

commonly used method of assessment. There are various steps to solving case

studies, the very first of which is understanding the ask. Here are a few tips to get you started:

Tip 31 – Listen carefully The first thing interviewers will do is give you the problem statement (e.g., is it a good idea to open a coffee shop in Dubai Mall?). What you’ll need

to do at this stage is listen and listen carefully. While some case studies are

straightforward, others are more complicated in terms of industry, geography, success criteria, the wording used, etc. Getting the given right is important, as getting it wrong might lead you to use an inaccurate framework, and we

all know what that means: Anchoring the whole case around an inaccurate structure isn’t ideal.

Tip 32 – Clarify, clarify, and clarify Once the interviewer gives you the ask, clarify anything that you might not have understood, as silly as it might be. I’ve heard a story of a candidate

who misheard “petrol station” as “metro station,” which led to 5 minutes of pure mutual confusion until both candidate and interviewer realized

the misunderstanding. Make sure you get the wording right and that you

understand both the context and the success. You can ask questions about 28

the industry itself, the company you’re about to assess, and the market you’re

about to size, just to ensure you go into case structuring with as much info as possible.

Tip 33 – Define success Do not ask for a few minutes and start structuring your case without first

understanding success. If it’s a profitability case, understand whether the goal is purely to estimate profits and, if so, over what period. If it’s a market sizing case, understand whether you should be estimating a value, revenues, profits, etc. If it’s a market entry case, understand if entering the market is purely

dependent on profits, and if so, what kind of profit margin would make the

investors say it’s a go. You get the point. These are just examples, but always

triple-check what you’re solving for before structuring your thoughts. Tip 34 – Rephrase and validate

A good practice to follow is to rephrase the given in your own words, which

is an extra layer of sanity check ensuring any misheard word is corrected and success is well defined. An example would be, “alright, my understanding

is that we’re looking into entering the dairy industry in France and that a

first-year profit margin of 10% or higher would be good enough for you to

enter. Therefore, the ask is to estimate the profit margin, with the end goal of deciding whether to proceed with the market entry or not. Is that correct?” Tip 35 – Ask for time Once you’ve listened carefully, you’ve clarified the given, you’ve defined

success, and you’ve rephrased accurately, always ask for a few minutes to

structure your thoughts. Use these few minutes to put the given aside (keep it on a separate sheet of paper), take a new piece of paper and lay down the

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structure you plan on following. This structure will become your reference and guide as you move forward.

Validate it with the interviewer before proceeding.

Do not jump straight into solving the case without a structure in place. That

would be like entering a new city without any map on hand. Know where

you’re heading and which components you’ll need to look into before starting the race.

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St ru c tu r i ng yo u r case f r om t he s tart CASE STUDIES TIPS Once you’ve understood the ask, you’ll need to lay down the structure

you plan on following throughout the entire session. Think of it as the

master plan you’ll refer to. The structure needs to be simple, effective, and

should clearly indicate how you’re planning to get to the final answer and

recommendation you’re asked to provide. Here are a few tips that will help

you put the right structure in place. It is, however, important to read the rest of the book (beyond these tips) to understand the various types of cases and which structure to use when.

Tip 36 – There’s no “one size fits all” Every case study is different (the industry, the company, the country, the

problem, the success, etc.). You’ll never be able to find a “one size fits all”

approach to your cases. You can, however, keep a set of tips in mind, and as

you learn to differentiate the types of cases (next chapters), you’ll be able to tailor the right structure depending on the case. Tip 37 – Keep it simple Keep things simple when you put your structure/framework in place. The

more complicated your structure is, the more difficult it will be to explain it to the interviewer and the more complex it will become to actually follow it throughout the session—you’ll have more items to cover, and it will be harder to connect all the dots towards the end.

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Simplicity is key. We recommend following a layered approach, starting with the 2-3 buckets you want to cover in the case (e.g., a macro-

economic overview, a company-level profitability assessment, and a final recommendation). This can be further detailed by putting some of the

components you want to cover in each bucket. For instance, you might start by listing down things you want to cover as part of the macro-economic

overview, like the state of the economy, the barriers to entry, political risks,

etc. For profitability cases, you can list down some revenue streams and cost buckets you will want to cover. For market sizing, you can note down some demographic and behavioral segments you’ll take into account.

But do not go deeper than that, and do not try to be comprehensive at this

stage. Keep the structure simple and clean, and do not engage in any sort of deep dive or calculations yet, as your whole structure might not be accurate

and will need validation from the interviewer first before detailing. This takes us to the next tip.

Tip 38 – Validate before proceeding After taking a few minutes at the beginning to lay down your structure, ask the interviewer if it makes sense. A sanity check is always helpful

as it prevents you from diving deep into a structure that is loaded with

elements you don’t really need. On the other hand, it also prevents you from

proceeding with missing elements. The interviewer will have to give feedback if asked, and that will help you fill in the gaps.

Make sure you cover the big buckets when summarizing the structure,

mentioning a few sub-buckets as examples throughout. For example, “I’m

thinking of first looking at the macro-economic factors such as the overall

state of the economy and any barrier to entry, then diving into the company’s financials, including revenues such as rentals and costs such as labor and 32

transport, to finally be able to give a recommendation. Throughout the case,

we’ll ensure we’re comprehensive in the assessment, but I wanted to get your initial thoughts on this first before proceeding.” Tip 39 – Love and hate frameworks Case study frameworks (e.g., 4Ps, the 5Cs, Porter’s 5 forces) are helpful as

they summarize nicely the various business fundamentals you need to know when solving case studies. I encourage you to learn these, and I love how

practical and memorable they are. However, interviewers are familiar with

these frameworks as much as you are, so dropping them as is will not only limit you and your structure but could also be interpreted as an inability

to tailor your own structures based on a given problem (which is what is

required of a good consultant on real-life projects). Keep a healthy balance; use the frameworks to learn the basics, but always tailor your structure depending on the case.

Tip 40 – Make it visual As you communicate your structure, always use visuals (e.g., a logic tree for market sizing, a

profitability tree for profitability cases, a graph if you’re asked to predict the sales trajectory,

a table if you’re asked to analyze various streams). It makes your life easier

as you will be able to locate your findings and organize them better. It also shows rigor.

For example, for the macro-economic assessment, you can use a small table

in which you simply list factors in one column and ticks in the other column

if these conditions are met. For the profitability part, you can use a logic tree, gradually splitting profits into revenue and costs and the latter into their

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various sub-components (e.g., fixed costs, variable costs, again split into labor,

utilities).

Tip 41 – Keep it separate and clean Once you’ve laid out your main structure, keep it on a separate sheet.

Avoid making side calculations in the corners, left and right, as you might

eventually lose track of these calculations and the numbers you’re deriving. You’ll also pollute your main structure, which is supposed to be your

north star as you go through the case from A to Z. Keep a sheet purely for calculations; you can structure that one as a big table with themes in one

column and calculations in the other (e.g., you calculate the volume of meals

that you expect to sell separately in that sheet, then you plug in only the final volume figure on the main sheet, next to the price and under the revenues). If the structure gets complicated, you can consider numbering the various

sub-items within it (e.g., if you have listed down 10 fixed costs, number them from 1 to 10 so that you also number the backup calculations in the separate sheet). This way, you can easily trace where the number you plugged into the

final framework comes from (e.g., where did the $2K rent figure come from? Rent is number 7 in my list. I check it in my calculations sheet; number 7 is where the detailed calculation of that $2K is). Tip 42 – Prepopulate partially to impress Do not keep your structure generic (e.g., profits equal revenues minus costs, that’s it). Pre-populate the structure—from the beginning, before you even walk the interviewer through it for validation—with high-level revenue

streams, potential costs, potential demographic and behavioral segments you want to consider if it’s a market sizing case, etc. Showing the interviewer that you already have an initial hypothesis on the various elements you’ll

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analyze during the session gives you an advantage over other candidates who keep things generic from the start and rely on the interviewer to help them populate the structure.

Tip 43 – Keep it MECE MECE stands for Mutually Exclusive and Collectively Exhaustive. Mutually

Exclusive means that there are no overlaps across the various parts of your

structure (e.g., revenues and cost are completely independent). Collectively Exhaustive means that the various components of your structure are

comprehensive (e.g., you’re not forgetting a revenue stream or a cost bucket

in a profitability case or you’re not forgetting a certain demographic segment in a market sizing case).

Keeping your frameworks/structures MECE is a core requirement in

consulting projects to ensure your client’s recommendation is as solid and

bullet-proof as possible. Showing you can do that in the interviews indicates

you’ll be able to do it on the job as well.

Tip 44 – Open with it, guide with it, close with it As mentioned before, your main structure is your north star. It’s the first

thing you put when organizing the problem statement, and it’s the last thing you refer to when you want to recap the final verdict. Open with it and close with it.

The structure can also be used as a guide for the interviewer. You can

even put the paper between you and the interviewer and start referencing that framework as you go through the case (e.g., so now that we’re done

with the revenue side of the business—pointing towards the big R in the

framework—we’ll move to the cost side—pointing towards the big C). This 35

indicates you can guide audiences as you present, which is a key skill to have as a consultant.

Tip 45 – Structure first, numbers later As you put down the structure, do not worry about punching in numbers and assumptions yet. You can do that once you validate the structure fully with

the interviewer and once you move on to the next part of the case, in which you take each of the various components and aggregate them bottom-up to reach the final answer/recommendation. Doing that will ensure you are not running unnecessary calculations as the structure might not be fully correct from the start.

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Cr ac k i ng th e case CASE STUDIES TIPS Cracking a case starts with putting the right structure in place, but that’s

only 2 minutes out of a total of around 30 minutes. The bulk of the session is typically used for you to dive deeper into your structure, ask the right

questions, get the right data points, and run the calculations to gradually

derive your final recommendation. Here is a set of tips you’ll need to keep in mind when moving from your high-level structure to solving the case. Tip 46 – Know the business 101s Consultants come from a variety

of backgrounds as the job requires

structured and analytical thinking far more than it requires deep technical

knowledge. That said, you’re still applying for a “management” consulting role,

and knowing the basics of business is important. At least at a high level,

you should understand a company’s financial statements (income statement, balance sheet and cash flow), what revenues and costs mean, what margins are and, more importantly, how a company runs.

During interviews, whenever possible, use business terms and don’t be generic. For instance, don’t say you’ll calculate how much money the

company will make; instead, say you will calculate its revenues and profits. This will show you have the business fundamentals consulting companies

require. If you feel you don’t know the basics, take a small break from reading this book and do some research. You should be all set within 1-2 days.

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Tip 47 – Don’t boil the ocean Do not go into every single detail when solving your case. A company might

have 50 cost items, but you might only need to mention the top 5-10. On the revenue side, a restaurant might have 50 items on its menu, but that doesn’t mean you should account for 50 revenue streams and the costs of each. You

can bundle cost buckets and revenue streams to keep things simple and clean. Tip 48 – Think macro, then micro Some of us have the tendency to dive deep into the company’s financials (the micro) without understanding the broader macroeconomic (macro)

context first. What if the entire country is at war and borders are closed? Is

the company’s profitability still the biggest factor to consider when assessing whether to enter the market?

The above example is a bit extreme, but that’s just to explain how important it is to relate back to macroeconomic factors before diving into the micros.

These include elements like the state of the economy, economic headwinds and tailwinds or barriers to entry. Taking a step back and doing a macro

assessment often shows rigor instead of diving straight into the framework itself (e.g., the company we’re analyzing). In most cases, macroeconomic

conditions are fine, and it’s actually the micros that you’ll spend most of your time assessing. Covering the macros does, however, show you get the bigger picture and that you’re comprehensive in your thinking. Tip 49 – Visualize the business Whenever you think of the structure you’re putting in place and the

fundamentals of a business, try to visualize the business in front of you: its headquarters, its branches, its logistics, its suppliers, its customers, its 38

operations, etc. This will help you drill down into the various revenues and

costs, minimizing the chances of missing something major. If you’re sizing a market, visualize where the products can be (e.g., every possible cell phone out there; where could it be beyond households, stores, landfills?). Tip 50 – Think outside the box Try to stand out by mentioning creative elements that other candidates might not think of. For example, if you’re

sizing the revenues of a coffee shop, it’s

interesting to mention that F&B might

not be your only revenue stream. You might consider selling merchandise or

putting a small arcade next to the shop. Interviewers appreciate outside-thebox thinking.

Tip 51 – What are you missing? Throughout the entire case, always ask yourself whether you’re only covering the obvious elements and whether you’re missing something. Maybe

you’re used to adding rent as a cost, but this facility is owned by the client

instead. Maybe you’re focusing on a single revenue stream, but there are two others you didn’t think about. Consulting interviews often include hidden information that the interviewer will only give or confirm when asked.

Always think outside the box and stay on the lookout for such elements. Tip 52 – Does it make sense? Whenever you derive a number or insight throughout the case, it’s important to step back and consider the bigger picture to show that you’re not just running calculations. For instance, if you find out that the volume of

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sandwiches a small restaurant sells daily is 20K, recognize it’s a big number for such a small business, flag this to the interviewer, and decide jointly on why it is the case (calculation mistake, unreasonable given or impressive performance?).

Tip 53 – Bake in some external knowledge You’re often given a set of data points and facts to run with, but this doesn’t mean you can’t add your own to the mix. If you’re solving a market entry

case and you know that the country you’re assessing is known for its geopolitical conflicts, mention that might be an extra risk to factor into the

macroeconomic assessment beyond what the interviewer mentioned. This will show that you’re thinking of the case as a real-life problem and that

you know how to put the business case into context. It also reveals strong business knowledge, which you’ll also need on the job. Don’t be pushy,

though; if the interviewer appreciated your input but advised you to disregard that new piece of information you put forward, it’s probably for the sake of

time. You should then follow their guidance without insisting on factoring in your new information.

Tip 54 – Cherry on top? Yes, please. When you get to the final recommendation, don’t stop at the obvious layer (e.g., the company will make a

margin of 10%). Add your own touch (e.g., 10% seems reasonable, as I know such industries typically have a

lower margin due to high competition. It’s also important to note that this

figure is for the first year, but it might be lower if new competitors enter the market. What do you think?). This takes you from good to great.

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Tip 55 – Solve for business objectives, not numbers Always focus on solving the business objective, not just the math itself. If

the profit margin you consider a success is a minimum of 10%, and the final margin calculation is 23.5248% x 50%, it’s clear that the answer is around half of 23% (which is around 11.5%) and that you’re already above your

target margin of 10%. Don’t focus on cracking the detailed math if you have already solved the business objective.

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A c i ng q u an t CASE STUDIES TIPS As you crack the case bottom-up (going into the components one by one and asking the right questions in many cases), you’ll often need to run

calculations to gradually derive the final figures. Being analytical is a big plus in consulting, as you’ll often need to work with data to derive key insights. When it comes to cases, getting the quant right and showing you’re not just quick but also structured and accurate is key. Here are some tips to

simplify the math for you. You’ll need to couple these with lots of practice to minimize mistakes during interviews.

Tip 56 – Use abbreviations As you start cracking cases, the math will

get more complicated. What is 2,000,000 x

1,500,000? It’s actually 2Mnx1.5Mn=3Tn. Don’t leave the decimals and the zeros

hanging. Use shortcuts in a way that you

work with 4-digit figures or less. Use K for

thousands, Mn (or M) for Millions, Bn (or B) for Billions, and Tn (or T) for trillions. The math becomes much simpler as you would only worry about the main digits, with units canceling out as needed (e.g., 6Tn/3Bn=2K,

5Mnx4K=20Bn). As your papers get messier and messier, having fewer zeros helps. Trust me 😉

Tip 57 – Decompose Another helpful tip is to break down formulas until you’re comfortable with their components. This could be done by expanding the formula or by using 42

fractions. An example of the first is 8x15=8x(10+5)=80+40=120. An example of the second would be 30x15.5=30x31/2=15x31=15x(30+1)=450+15=465 Tip 58 – Prove yourself, then take proxies You’re not expected to get the exact number right in every calculation, meaning you can take proxies throughout the interview. However, it’s recommended to get a few numbers 100% right at first to show the

interviewer you’re comfortable with the math and that you’re only taking

proxies given the tight time and for the practicality of calculations, rather than due to poor quant skills. Get a few right, then start taking proxies.

When you do so, however, it’s important that you greenlight this by the

interviewer first (e.g., “do you need the exact number or can I take a few

proxies here?”)

Tip 59 – Don’t shoot yourself in the foot; go for easy numbers When asked to make assumptions, choose round numbers you’re comfortable working with. It’s true that the interviewer might sometimes give you a few data points you can’t control, but at least control the ones you’re adding to

the mix. Running the math under pressure is already difficult enough, don’t add a layer of complexity.

As an example, if the rental price per sqm is $200 and you’re estimating the size of the property, don’t go for 97sqm as an estimate; go for 100sqm and make your math easier (100x200=10x2K=$20K). Tip 60 – Accurate math > quick math Don’t rush into providing final figures if you’re not at least 90% confident that you’re getting it right. Quick and inaccurate math is far worse

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than slower and accurate math. When you feel the calculation isn’t

straightforward, ask for time and do it right (e.g., “can I have 30 seconds to run the math, please?”). Ideally, you would be quick and accurate, but that takes practice, starting with the latter and gradually improving the speed. Tip 61 – No awkward silence If you feel there’s a lot of silence during the interview as you crunch numbers, walk the

interviewer through your logic and through

the numbers (e.g., “So 8 times 15 is nothing

but 8 times 10 plus 5, this gives us 80 and 40,

meaning the total number of cars is 120”). This

breaks the silence and gives you the time you need to crack the calculation. It also verbally shows the interviewer you’re using shortcuts and running clean math. You don’t need to do that for every single calculation, but this can come in handy for quant-heavy cases.

Tip 62 – Drop the ego, ask for help if needed If you really feel you’re stuck and the interviewer wouldn’t accept you taking proxies, it’s okay to ask for help. Is it ideal? No. However, it might be best

to get some help and proceed to other parts of the case where you can shine

more rather than dragging over one part only and risking not having enough

time to complete the case. It might also be interpreted as a humble act and as

willingness to learn and improve.

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Tip 63 – Seek validation rather than forgiveness When you’re doing multiple calculations in a row, don’t just communicate the answers; validate them with the interviewer, as some might leave you

on a roll without telling you whether you missed something or not. When

asked if the numbers make sense, the interviewers HAVE to tell you whether you’re right or wrong. This helps you to know if you’re on the right track and

whether there’s a mistake somewhere, in which case, they’ll probably ask you if you’re sure about the answer or if you would want to double-check the

math. Again, this is not needed at every single step of the way but can be helpful, especially after long and complex calculations. Tip 64 – Don’t misplace your findings When you finally get to the answers, note these down in your main structure or framework (e.g., if you have just calculated the volume of sales, put it

in your profitability framework that should be kept on a separate piece of paper). Why? Because many people underestimate how much pressure

they’re under in these 30 minutes and end up misplacing the numbers they calculated throughout. Separate calculation sheets from the main structure sheet in which you plug in the core findings.

Ideally, you should keep your calculation sheet clean as well. While all

candidates attempt to be structured in their main framework and in their communications, you can stand out by maintaining structure even in the smallest of details. When running side calculations, use a mini logic tree

there, even if it’s only 2 layers of calculations. Some interviewers watch you noting down things and might even take your papers once the interview ends. Don’t leave any unstructured marks behind.

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Tip 65 – Meet your biggest enemy: Units As you run calculations and note these down in your framework, always note

down the units as well (e.g., are the sales

you found monthly or yearly? Is the cost of raw material per KG or per Ton?) A

mix-up in units can lead to numbers far below or far above the actual answer, so keep that in mind!

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1 0 c a s e s t u d i es ti p s, c o m m u n i c ati o n So far, we’ve talked a lot about what you need to cover as you solve cases (the given, the initial structure, the case deep dive, and the quant). But we have

not yet talked about the way you should be communicating throughout the

session. Good communication skills are also something interviewers look for, and communicating your answers properly is as important as getting them right. Here are a few tips to improve your communications skills: Tip 66 – Articulate It’s important to articulate as clearly as possible when talking to the

interviewer. Combining words and letters might make it harder for them to understand what you’re saying, especially if they’ve conducted several

other interviews on the same day/week and are not very focused. Polished communications indicate you’ll be clear and concise when put in front of clients, which is definitely something interviewers will be looking for. Tip 67 – Communicate top-down When communicating, start with the “so what” (the insight), then present the arguments. This method, also

called the pyramid principle, ensures

you provide the interviewer with the answer first (and with that reassurance that the route followed is correct) and then support it with the details. If

you start the other way around (bottom-up), the interviewer might lose your train of thought mid-way, as they would have no clue where you are in the

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reasoning and which conclusion you’re headed towards. In this case, you can

say something like, “It makes sense to enter the market given that it’s a stable economy, that there are no barriers to entry, and that the 10% profitability

condition is met”; instead of saying, “So we analyzed the economy and found out that the macroeconomic factors are stable, we also looked at barriers to

entry, and there were none, to finally move to profitability where we derived a 10% profit margin. That’s why we’re concluding that we should enter the market.”

Tip 68 – Synthesize, don’t summarize You’ll be required to recap your findings across multiple stages of the case

interview. The most important recap happens towards the end when you’re

giving your final recommendation. Nevertheless, it’s also important to take a

step back periodically throughout the case and review what you’ve learned so far. This will help dictate the way forward.

When recapping, don’t limit it to a pure summary of what you’ve done so

far (e.g., you’ve calculated revenues and costs); instead, synthesize the main

findings (e.g., you’ve so far estimated profits at $20M implying a 10% profit

margin). A synthesis gives the “so what,” while a summary simply recaps the facts.

Tip 69 – Don’t use fillers You should maintain polished and structured communications throughout

the session. One thing that helps is avoiding fillers such as “you know,” “like,” “I mean,” or “look.” This will distort the essence of what you’re trying to say.

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Tip 70 – Stay formal; you’re not among buddies Do not use slang and informal vocab. Stay formal throughout your

communication, and use proper grammar.

Do not refer to the interviewer by their first name unless given permission. Stick to the official language you’re interviewing in, even if you know the

interviewer can speak another language. For example, in the Middle East,

interviews are conducted mostly in English, although many candidates and interviewers are Arabic speakers. You should stick to the official language, as mixing languages might be interpreted as informal. If the interviewer

speaks to you in multiple languages, you can follow their lead by dropping in a few words in the native language here and there but keep the bulk of the communication in the official language. Tip 71 – Pause, don’t ramble When you’re thinking in between sentences, take a solid pause (silent

moment), do not make unpleasant sounds and ramble as you transition

between phrases (e.g., “ok, so after calculating costs—euuu. I’ll probably

think of—euuu—going into revenues”). It’s as bad, if not worse, than using word fillers.

Tip 72 – Be open to feedback and guidance The interviewer might guide you when they feel you’re not on the right track or if they want to steer you in a specific direction. Don’t get defensive, as

that’s the last trait companies look for in a consultant. If you’re challenged, provide your point of view without refuting theirs. Otherwise, you might come off as stubborn or hard to work with.

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Tip 73 – Don’t offend the interviewer Be polite from the moment you enter the room to the moment you leave it. Don’t say anything that might offend the interviewer directly or indirectly.

Examples can include making assumptions that might be interpreted negatively by specific demographics or groups. Tip 74 – Be politically correct

You will sometimes be put in situations where the company, country or case being discussed is socio-politically sensitive. Solve the case objectively and do not provide any personal opinions that might show direct bias towards

a certain social, political or economic topic. It won’t help you solve the case

nor impress the interviewer, especially if the interviewer does not share your same point of view.

Tip 75 – Use light humor if suitable With humor, you can break the ice and defuse the tension of the interview.

Think of small and gentle ways of keeping the conversation comfortable, and don’t overdo it. If you feel that the interviewer or the HR are joking with you, follow up with some light-hearted responses.

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Q /A a nd c l o s ure ti p s Tip 76 – Don’t wing the Q/A Do not try to wing the Q/A part of the interview, and more importantly, come prepared with questions in mind. It might take hours to come up

with one interesting question to ask, and you don’t want to improvise on the spot, trust me. Read the room and do not insist on asking the questions you prepared if the interviewer has already, directly or indirectly, answered these at some point in the chat.

Tip 77 – Always ask questions This is probably one of the most common tips you’ll get, but you’ll be

surprised by how many people still respond with “Mmm, I think I’m okay. Thanks” when asked if they have any question in mind. You can’t possibly know everything about the company, your interviewer or the role you’re

applying for. Not asking questions therefore means you’re not interested in knowing more and will not be interpreted well by interviewers, especially when compared to other candidates who would have prepared a list of impressive questions to ask.

Tip 78 – There are wrong questions Know ahead of time which questions to ask and which questions NOT to ask. For instance, do not ask the interviewer anything related to your interview performance (e.g., how did I do?), your compensation or any

HR-related question (e.g., base location, next steps in the process). These are better discussed with HR, and you might portray yourself as too superficial

or materialistic if you direct these to the interviewers instead. Plus, most will 51

not really know how to answer these, as they are here to test your behavioral and technical skills, not handle your recruiting process.

Tip 79 – Balance personalized and company questions The more you connect with the interviewer, the

higher your chances of passing to the next round. If you’ve gathered enough information about

them, the industry they focus on or the projects

they do, ask them a personalized question. Many people love talking about their own experiences and careers, and the more they do, the more you should express interest. You can do that

by nodding your head and asking follow-up questions.

A few examples of such questions would be: • • • • •

What was your best project so far, and why?

Looking back at your consulting career, what did you enjoy the most vs.

the least?

Do you think of consulting as a long-term career or is there another industry or field that interests you? Why did you join this company?

Why did you become an interviewer?

However, if you sense that the interviewer isn’t comfortable sharing his/her own experiences (they’re giving short answers and don’t appear engaged), switch to more company and industry-related questions instead.

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A few examples of such questions would be: • • •

How big and active is the financial services vertical in your company? Does the company provide training programs in key skills such as modeling or problem-solving?

What are the different career tracks we can follow in our consulting career?

Typically, a combination of personalized and company/industry level questions works best.

Tip 80 – One question at a time Keep your questions short and concise, and do not ask too many questions at

once, as it might confuse the interviewer, leading them to partially answering your questions. Ask the first and get your answer before proceeding to the next.

Tip 81 – Let them finish Do not interrupt interviewers while they answer your questions. Let them finish and note down any comments or follow-up questions you may

have. Apologize if you accidentally interrupt them, and acknowledge their statements.

They shouldn’t get the impression that you memorized a couple of questions and aren’t really interested in the actual answers they’re giving. Give each question the time and attention it requires. Tip 82 – Drop your agenda as needed You might need to just drop the other questions you prepared if one 53

question leads to another, and you suddenly find yourself in a very enjoyable

conversation with the interviewer. Leverage the momentum and dive deeper into any topic that seems to be flowing well. You might end up asking one

question only, but it would have been worth it. You should also monitor the

interviewer’s reactions and behavior. If you feel they’re interested, dig deeper. If you feel they’re offended or bored, change tactics. Read the room. Tip 83 – It’s not Q; it’s Q&A. Listen to the answers. Don’t lose focus after answering the question. Listen to the answer. When listening, express interest via facial expressions or gestures, stay engaged in the discussion, and do not come off as bored or uninterested. The

interviewers are taking some of their own time to answer questions you specifically came up with.

Tip 84 – It’s a section for you Keep in mind that the purpose of this section is to answer questions

you might have. Obviously, you are still in an interview setting, so any

opportunity to impress or sound interesting should be leveraged. However, if

you have key questions you would really want to hear the answer to, now is the time.

Tip 85 – End on a high note Don’t end the discussion abruptly. Find a comfortable and enjoyable moment to reveal that you no longer have questions and that you really enjoyed the

chat. Ensure you don’t end the discussion right after engaging in a boring or sensitive topic. Cover exciting topics right before you wrap things up.

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P os t i nte rvi ews Tip 86 – Stick around a bit When you’re done with your interview, stay around and talk to the other

interviewers or to the talent acquisition team that might be around. It doesn’t hurt to show interest beyond your interview and to get to know the wider

team. You never know who from that group has influence, and leaving a good mark across the wider group might be in your best interest. As mentioned

before, all the interviewers typically get together as they decide on the final verdict, so at least they’ll have a face to the name when doing that. Tip 87 – Ask for their contact details Do not rush out of the room as soon as you’re done with the interview. You

just met an interesting and probably senior person in the industry you want

to work in. Ask politely for their business card or any contact details they are comfortable sharing. This reconfirms your interest in keeping in touch and allows you to send thank-you and follow-up notes as needed. You can also

connect with them on networking platforms such as LinkedIn a few days after the interview.

Tip 88 – Run a self-assessment and note down your learnings Think of anything you would want to remember from this interview. It could be as simple as the name of the interviewer or the case study you had to solve. It could

also be mistakes you know you’ve made, and you wouldn’t want to make again in future

interviews. Reflect back on the full interview 55

(the fit part, the case part, and the Q/A) and note down any learnings for

future reference. Do not overestimate the capacity of your memory, and try

to record these insights as soon as you reach home. You can even do that by recording a small voice note to yourself on your way back home. Tip 89 – Send a few thank-you notes It’s good practice to send out a few thank you emails to your hiring manager when you’re done with the process and to your interviewers within 24 hours

of the interviews. Keep them short and sweet, as the interviewers might have a lot on their plate. Such a gesture is appreciated and shows commitment

to getting the role. Do not include questions in the email (e.g., feedback

on your performance); it’s just a thank you note. However, you can include a recap of when and how you met, as well as why you’re interested in the opportunity.

If you want to impress, you can even send some news or literature references to a topic of discussion you’ve covered in your interview or interactions. For

example, if you’ve discussed the shortage of chips in the automotive industry, send an interesting article that you came across. Tip 90 – Stay connected After the interview, follow up with the talent acquisition team from time to time. This could be done via emails or messages, depending on the way you

have been communicating. This helps you know where you are in the process and shows your excitement.

Additionally, you should also stay reachable in case you get any email or call from the company. Return any missed call as fast as possible, and be sure to do that during working hours. Do the same for emails. 56

Tip 91 – Don’t burn bridges Maintain a good relationship with all the companies you interviewed with. Answer or return any call or email you get and maintain a good image.

Ask to be withdrawn from the process if you’re no longer interested in the role (e.g., you decided to go for another offer) to avoid receiving an offer

and declining it. You never know when you’ll cross paths again with these companies (it’s common practice to move around within the industry), so

stay on everyone’s good side. If you’ve already been given an offer and must

decline, do so in writing and indicate why you made the decision.

If you’re rejected, you can consider replying to the rejection letter and

thanking them again for considering you. These small things matter and can increase your chances if you ever decide to apply again. Tip 92 – Don’t follow-up excessively Again, don’t overdo the follow-ups (once every 1-2 weeks is fine, and with talent acquisition mainly). Following up excessively might indicate that

you’re desperate for the role, which raises questions (why are you that eager to join? Have you been struggling to find a job and you desperately need one? It might not be the case, but don’t give them ideas). Tip 93 – Be comfortable with waiting It might take a while for the hiring team to screen all candidates. Some

might be invited for follow-up interviews, and others might take some time

to come back with the requested documents. All of that is to say that hearing back from the hiring team doesn’t usually happen overnight (although it might). Follow up regularly and politely, but don’t stress about it.

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Tip 94 – Negotiate when you can Once given the final offer, the tables turn, and you start to have the

negotiating power. They clearly want you; otherwise, they would not have

extended the offer. Ask for more, but stay reasonable. If it works, then great; if it doesn’t, don’t be too pushy.

If you have multiple offers from multiple companies, let them know you do. This will raise your market value and will ensure talent acquisition teams

expedite your process and make your offer as competitive as possible. Don’t forget, they compete against each other. Tip 95 – Feedback is precious; take it Whether you made it to the next round or you got rejected, ask for feedback and listen carefully to what is being said to you. These are important tips

on real-life interview performance, which will come in handy in future

interviews, whether for consulting or beyond. Whatever you think your interview strengths and weaknesses are, it’s through real-life interview feedback that you’ll really validate those. Tip 96 – Don’t rush into signing Do not rush into signing an offer as soon as you receive it. Even if you’ve

spent months preparing for those interviewers, and even if you think you’ve

landed the dream offer, make use of the time you’ve been given to revert back to the hiring team, at least partially. You can use that time to complete other

recruiting processes and, if necessary, to compare various offers. Compare the offers but also reassess the company’s culture, brand, team, compensation,

base location, and any other factor of interest before signing. The offer isn’t going anywhere. 58

Tip 97 – Take a well-earned break Once you sign, make sure you take some good time off before you start your job.

Do not worry about Excel modeling and other skills you will need on the

job, as most companies offer extensive onboarding and training programs to

ramp you up. Plus, work-life balance in consulting isn’t perfect, meaning you should embrace the time off while it’s there. Tip 98 – Find your new buddies As you get closer to your onboarding date, try to connect with some of your

future colleagues, especially the ones that come from a similar background as you (e.g., same high school, university, MBA or company). Knowing people on the inside before joining can help you navigate the company better once

you’re in. For instance, you can find out about industries that are interesting

and teams that are nice to work with to avoid random staffing upon joining. Tip 99 – Don’t rub it in people’s faces After signing, stay humble and refrain from bragging about the offer. Keep

in mind that many of your peers might still be in the middle of their process. Cascade your learnings to others and help them get in. The more friends you have in the industry, the better!

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Tip 100 – Go kill it 🙂 If you made it through, then you have all it takes to become a counselor to top companies and leaders globally. Apply everything you learned before, during, and after the interviews to start what will surely be a successful career. Go kill it!

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chapter two

Most Common Case Studies

The more case studies you solve, the more you’ll realize they’re not so

different from one another after all. The newer you are to the game, the harder it is to spot these similarities. Here’s an example:

I’m thinking of opening a coffee shop in London. What do you think? The above is just another way to ask the candidate to estimate the potential

profits a typical coffee shop makes in London. If you go ahead and ask some clarifying questions to define success, you’ll quickly realize it’s the business’s

profitability that will determine whether the interviewer would want to open a coffee shop. That example can therefore be categorized as a profitability case, to which we dedicated a full chapter later in the book.

So what are the various types of case studies, and how do you unmask them in the interview?

Let’s first understand the various types, then dive into them one by one to learn how to crack them.

1- Market sizing (detailed in Chapter 3) Market sizing is about estimating the volume of products, sales or events based on a set of defined metrics. It’s typically through such cases that

interviewers measure your ability to structure a certain problem, think of the relevant factors to consider, and run some quick quant to gradually estimate the end figure.

There are direct ways of asking the candidate to size a market, such as: • • 64

How many cars are there in Japan?

What is the total volume of headphones sold per year globally?

•

How many people are wearing blue today in Beijing?

There are also slightly indirect ways of asking the same questions. That’s

typically done by adding some context or fictitious scenario to the question before asking it. Here’s an example: •

Some scientists discovered a cure for cancer. What do you think would

be their total sales?

In this example, the ask is still to estimate the total number of people willing to pay for a cancer treatment. It’s just framed differently. 2- Profitability (detailed in Chapter 4) In profitability cases, you’ll be asked to either estimate or assess a company’s financials and profitability. There are various subtypes of profitability cases depending on the reason why you’re estimating profits. For instance, the ask can be as direct as “estimate the profits of a coffee shop in London.” However, it can be slightly more complex than that.

Market entry cases: One major subtype of profitability cases is market entry. In these cases, you’ll be asked whether entering a certain market makes

sense or not. The profitability of your business upon market entry is usually one of the biggest factors to consider when assessing whether it’s a good opportunity or not.

Dynamic profitability cases: Another sub-type of profitability cases is what we call “dynamic cases.” In these types of cases, you’ll be asked to explain

a certain variation in a company’s profitability as opposed to sizing it. For instance, a company could be losing money, and you’ll be brought in to identify the cause of that.

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New business cases: Another sub-type would be cases about new businesses and whether it makes sense to open them. Again, a big factor to consider when opening a business is the profits it will make, and therefore, a profitability assessment is also required in this case.

In Chapter 4, you’ll learn the typical profitability structure to use in any of

the situations listed above. You’ll need to adapt these learnings depending on the case you’re given.

3- Merger and Acquisition (detailed in Chapter 5) M&A cases revolve around a company merging with or acquiring another.

That company can be a normal business with synergetic business models or an investor (e.g., private equity firm) interested in acquiring.

A common reason for acquiring a business is to increase profits in both

the parent and acquired companies. Such an increase typically comes from revenue synergies (cross-sales, bundling, etc.) as well as cost synergies

(including consolidation of fixed costs like procurement and office space as well as consolidation of operations, which also affects variable costs).

As a result, there is an overlap between M&A cases and profitability cases, given that both require a financial assessment. However, M&A cases are

also heavy on conceptual problem solving (go beyond the numbers and the financials).

In Chapter 5, we’ll be going over M&A cases and how to go about cracking them.

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4- Pricing (detailed in Chapter 6) The last type of case studies is pricing. You’ll know it’s a pricing case when

you’re asked to price a certain product or service, although most of the time, such an ask is baked into a broader profitability case.

An example of such a case study is “Bank X is adding a new credit card to

their product mix, and they want you to advise them on how much to price it.”

There are multiple factors to consider when pricing a product or a service, be it your own costs, the demand for it or the competition. In Chapter 6, we’ll be covering the basics of pricing case studies. 5- Other case studies Although the tips provided above cover more than 80% of the cases you can get during interviews, the interviewer can always venture into uncommon grounds. Here are some examples to keep in mind:

Non-profit cases: Candidates may become confused when success isn’t

profit. But these cases exist, and success can be a social outcome rather than profitability. However, at the end of the day, you’ll still be able to apply a lot

of learnings from various case types as you think of these. Understand what success is really about (e.g., is it about curing as many patients as possible? is it about minimizing factory emissions?) and break down the entity

operations to identify potential drivers to increase or decrease these figures.

For example, decreasing emissions could be about cutting down on any

operation involving emissions and replacing it with greener initiatives. You’ll therefore need to list down all the key operations and examine each

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separately to see which ones can be cut down and how. As long as you have learned the art of structuring problems, you’ll be okay.

Personal cases: Some interviewers like to use the case study section to

have a random discussion with you to gauge your level of thinking. They occasionally present you with personal cases to solve. For instance, they

could ask you how you would go about organizing your wedding or how

you would think of building your first house. Sit back, relax, and enjoy the conversation. As long as you take that question, break it down into the

numerous components that feed into it (e.g., planning your wedding is about (A) getting the right attendees, (B) having the right venue/location, and (C) providing the right experience) and tackle them one by one. The interviewer

is probably just interested in the way you think. You’ve known them for only a few minutes; I don’t think they’re really interested in your wedding.

Real-life cases: Some interviewers, particularly the senior ones, might ask

your opinion about a real-life project they’re currently managing. It might not be about the full thing but rather about a specific stream. It might

be because they’ve spent the entire week thinking about it, and getting a

fresh pair of eyes is always helpful—you never know. An example could be: “I’m currently handling a big merger in the region, and trying to align the

merged company’s organization structure with benchmarks will mean cutting down the workforce by 30%. Would you recommend that?” In these cases, apply the same fundamentals we’re teaching you in this book (understand the given, clarify, structure, communicate properly, etc.), and you’ll do just fine. In this example, you’ll need to understand what the end goal of the

merged company is (profitability only? or does it, for example, include brand reputation as well). Based on that, you’ll be able to come up with various options to consider a rationale for each.

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Chapter Three

Market Sizing Case Studies

I ntr o How many baboons are smiling as we speak? Do you know? Well, me neither. The truth is, no one really knows, not even your interviewer.

Market sizing is about estimating the volume of products, sales or events based on a set of defined metrics. Such cases are typically brought to the table to test the candidate’s ability to take a vague problem statement, structure it, and tackle it layer by layer until an estimate is reached.

As complex and intimidating as these cases initially sound, you can crack them relatively easily if you apply the right fundamentals.

Clarify what you’re really sizing. The more questions you ask upfront, the

more you understand what you’re asked to estimate, e.g., if asked how many

cellphones are in London right now, it would be important to understand from the get-go whether the interviewer is referring to every possible

cellphone out there (the ones that people are currently using, the ones

people have but no longer use, the ones that are still in stores, the ones that

have already been disposed of, and so on) or just a portion of that. Typically, it’s important to clarify the what (what are we sizing), the where (which

geography are we sizing it in) and the when (over which period of time are we sizing it).

Break down the complex question into smaller variables. This is the most

important part of the process, and it’s typically in these few minutes that you make it or break it. It’s basically figuring out the master formula that will get you to the estimate you’re looking for. Here’s a simplified example of sizing the volume of diapers in France:

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Volume of diapers in France in 2021

Volume of babies in France in 2021

France popula�on in 2021

Diapers used / baby / day

% babies (0-2 y.o)

In this step, it’s very important to take few seconds to visualize all the subevents that could be relevant to our problem statement (e.g., if we’re sizing

diapers, who wears diapers? Maybe we need to account for adult diapers as well). No case is typically extremely straightforward, and it’s important we pause for a moment and think, “Ok, so what are the most important subevents in which my product exists?” Calculate Once the structure is established, you start by going bottom-up (from the

deepest layer in the structure up to the main question you’re trying to solve). As you attempt to fill in the numbers, you’ll quickly realize that you don’t

really know them all (e.g., you might not know the exact population size of

France or how many times a day we change a baby’s diaper). But again, who

cares? The interviewer isn’t here to test your expertise in baby diapers! What 73

you’re being assessed on is your way of thinking—your ability to come up

with the best proxies possible, given what you know. That’s why it’s important to have a good rationale for each number that goes on your paper as you start going bottom-up to populate your logic tree.

So, where do you derive your assumptions from? It could be numbers you’re sure of. In that case, you can simply say, “I know that the population of

France is around 65M.” However, you might only know a few numbers

here and there, which means you’ll need to estimate the others. In order to estimate numbers, consider referring to personal experiences (e.g., when

you saw your cousin last year, she excused herself every 3-4 hours to change her baby, which means that the baby requires around 6-8 diapers a day). In that last example, the number isn’t actually very accurate (the baby actually requires fewer diapers a day than that), but the fact that we applied quick

logic and math to a real-life experience indicates rigor. The percentage of the population who are considered babies can be taken as 3/80 or 4% assuming

that babies are 0-2 years old and that the life expectancy is around 80 years.

Volume of diapers in France in 2021

Volume of babies in France in 2021

Diapers used / baby / day

7 France popula�on in 2021

65M

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% babies (0-2 y.o)

4%

Consolidate You’ll still need to give your final answer to the interviewer after punching

in all the numbers. This requires a top-down summary of the final number,

starting from the number we reached, followed by the master structure that was used and a quick summary of the calculations.

Volume of diapers in France in 2021 18M

Volume of babies in France in 2021

Diapers used / baby / day

2.6M France popula�on in 2021

65M

7

% babies (0-2 y.o)

4%

As several assumptions have been made in the process, it’s always helpful to remind the interviewer that these are just proxies.

In summary, start by clarifying what you’re solving for to avoid wasting

time going into unnecessary details. Break down the ask into a clear master formula, plug in your various assumptions to fill in your formula while

ensuring you have a strong rationale for each, and finally consolidate the numbers bottom-up before recapping the final answer and logic.

Now, as mentioned before, theory is cute, but practice is king. A lot of the

concepts mentioned above can be found in various books and articles. The

value of this book is in the next section, in which you’ll be able to practice, practice, and practice with the goal of perfecting the art of market sizing.

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C a s e s tu dy 1 HOW MANY PEOPLE ARE WORKING OUT RIGHT NOW? Level: Medium Skills required: Coupling market sizing with the probability of a given event Given: How many people do you think are working out as we speak? [STOP] On the next page, you’ll find a guide to solving this case, which includes the steps provided below: Step 1 - Clarify the given

Step 2 - Break down the problem Step 3 - Calculate

Step 4 - Consolidate If you’re practicing on your own, make sure to only look at the part of the guide that is relevant to the step you’re currently at and only do so after

you’ve completed that step. For instance, ask yourself what questions you can ask to clarify the given, then look at step 1 in the guide before moving on to step 2.

For now, you can start by thinking of any clarifying questions you would want to ask before moving on to the next page.

If you’re playing the role of the interviewer, go through the full guide first and use it to steer the candidate in the right direction across all the steps.

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B e g inn in g o f gui de Step 1 – Clarify the given You’ll find below a series of questions that could be asked to clarify the given before structuring the case.

If you’re practicing on your own, take a few minutes to compare these to the ones you had in mind.

If you’re playing the role of the interviewer, guide the interviewee with the below only if he or she asks. •

Define the “what”: By people, do we mean every single person, including

•

Define the “what”: By “working out,” do we mean hitting the gym or

regular people, athletes, youth, elderly, etc.? does that include any type of sport?

Answer: We can include any person hitting the gym as we speak. •

Define the “where”: We have not specified the geography we’re talking

about. Are we talking about the US only or is that a global market sizing question?

Answer: Let’s say it’s global. [STOP] if you’re practicing on your own, complete the next step (break down the problem) before continuing to read this guide.

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Step 2 – Break down the problem If you’re practicing on your own, compare the structure you put to the below and double-check that you did not miss any demographic or behavioral factors.

If you’re playing the role of the interviewer, compare the candidate’s structure to the below and challenge him/her as needed. In case the candidate misses an important factor, guide him/her until the structure is complete.

Volume of people in the gym now globally

Volume of people typically going to gyms

Probability of them being there right now

Global popula�on

% popula�on going to the gym

% fi�ng the age

% financially capable

% mo�vated to go

Here is why the structure above works. We can start by stripping out the

“now” element from the main question. Any case study centered around an

event happening at this exact moment in time can be broken down into the volume of the event itself as well as the probability of it taking place at this

specific point in time. We’ll get to how we actually estimate that probability 78

in a bit. As for the volume of events (i.e., people typically going to gyms),

this can be extracted by taking the total population and multiplying it by the

portion that goes to the gym. That portion is best calculated by applying a set of metrics like age (some people just can’t go to the gym because they are too young or old), social status (some can’t afford it) and interest (some are the right age but just don’t like going).

[STOP] if you’re practicing on your own, complete the next step (calculate) before moving on to the rest of this guide. Keep in mind that your

assumptions, calculations and results in that next section can vary from mine and that’s completely normal. I will be taking quick proxies in some cases

and will not be justifying every single step to avoid overcrowding the book with details.

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Step 3 – Calculate

Volume of people in the gym now globally

Probability of them being there right now 2%

Volume of people typically going to gyms

Global popula�on

% popula�on going to the gym

8Bn

% fi�ng the age 60%

% financially capable 60%

% mo�vated to go 1/3

As mentioned before, the calculation step happens bottom-up (from the bottom of the tree to its top).

If you’re practicing on your own, compare your notes to the assumptions taken here.

If you’re playing the role of the interviewer, push the candidate for strong

assumptions backed by facts or personal experience. Do not let the candidate make wild guesses.

Let’s start with the easy parts:

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• •

Global population: This should be straightforward. The global population

is around 8 billion.

Percentage of people who are in the right age categories: By removing people aged 0-20 and 70-80 and assuming a life expectancy of 80, we

can assume that 50/80 of people are eligible, meaning roughly 60%. It is true that excluding these brackets fully might not be fully accurate (e.g.,

some 18y.o do work out), but keep in mind that the end goal is to get to a rough proxy and to focus on the segments with highest concentration

of the desired event (in our case, the people who are most likely to go to the gym). •

Percentage of people who are financially capable: For simplicity, we can

assume that the middle class and upper class individuals have access to a

gym (if they want to) which leaves us with around 60% of the population given that, in general, the Low:Middle:Upper segmentation ratio is roughly 40%:35%:25%. •

Percentage of people who are motivated to go: In the absence of concrete information or data regarding this, we can refer to personal experiences to try and estimate that percentage. Personally, if I think of a generic

sample of people I know, around 1/3 of them work out. Given that my

network is pretty balance demographically, I can extrapolate that figure and use it in my market sizing.

The only assumption left for us to make is the probability of these people

being at the gym right now. Now this one is a bit trickier, especially for first-

timers. What you should not do is throw a number (e.g., let’s assume 5% are

in the gym right now). Why is it 5%? Why not 1%? Why not 20%? We need a strong rationale.

The best way to come up with these probabilities is to take a more extensive

period (e.g., 1 week), plug in the events, and then translate that into a “now” 81

probability. We can, for example, assume that people go to the gym, on

average, twice a week (when they do). This means that around 4 hours a week are spent in the gym and that if you randomly caught those people every

week, there would be a big chance they wouldn’t be there. In fact, from the 7 days (or 168 hours), they are there for 4 hours only, which means that if

you crash the gym at any point in time, there is a probability of 4/168=2/84= ~2% of them being there. Now that 2% is definitely stronger than the 5% we

first randomly assumed.

Note: The candidate should always validate all the assumptions with the interviewer before proceeding with the calculations.

[STOP] if you’re practicing on your own, complete the next step (consolidate) before continuing to read this guide.

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Step 4 – Consolidate

Volume of people in the gym now globally ~20Mn Probability of them being there right now 2%

Volume of people typically going to gyms ~1Bn

Global popula�on 8Bn

% fi�ng the age 60%

% popula�on going to the gym 12%

% financially capable 60%

% mo�vated to go 1/3

As we finalize the calculations, we’ll need to synthesize top-down our

findings, starting with the solution and drilling a bit deeper into the various layers.

A good wrap-up would be: “Based on various assumptions we discussed, it looks like there could be

around 20 million people at the gym right now. We arrived at this figure by

estimating the total volume of people who typically go to the gym, which is

around 1Bn and multiplying it by the probability of them being there, which is 2%. Various other metrics were taken into consideration as we got to this number, including age, social status, and interest in hitting the gym.”

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An important note: You’ll notice that in other interview preparation workbooks, certain solutions often call for starting with the population and drilling down segment by

segment into age, social status, motivation, and other metrics, before adding

a probability to the outcome. I consider such an approach a more tactical way of doing things since you don’t really know where you’re heading (e.g., you

take the population, trim from it, then trim more, then trim more, hoping to get to the volume of people who work out). The method we’re using above

starts top-down from the result we’re looking for. That way, you can ensure your breakdown aggregates up to the intended solution.

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C a s e s tu dy 2 HOW MANY PLANES ARE CURRENTLY IN THE AIR? Level: Medium Skills required: Coupling market sizing with the probability of a given event Given: How many planes are currently in the air? [STOP] On the next page, you’ll find a guide to solving this case, which includes the various steps provided below: Step 1 - Clarify the given

Step 2 - Break down the problem Step 3 - Calculate

Step 4 - Consolidate If you’re practicing on your own, make sure to only look at the part of the guide that is relevant to the step you’re currently at and only do so after

you’ve completed that step. For instance, ask yourself what questions you can ask to clarify the given, then look at step 1 in the guide before moving on to step 2.

For now, you can start by thinking of any clarifying questions you would want to ask before moving on to the next page.

If you’re playing the role of the interviewer, go through the full guide first and use it to steer the candidate in the right direction across all the steps.

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B e g inn in g o f guide Step 1 – Clarify the given You’ll find below a series of questions that could be asked to clarify the given before structuring the case.

If you’re practicing on your own, take a few minutes to compare these to the ones you had in mind.

If you’re playing the role of the interviewer, guide the interviewee with the below only if he or she asks. •

Define the “what”: By planes, do we mean all types of planes, including commercial, military, cargo, etc.?

Answer: No, let’s just focus on commercial flights. •

Define the “where”: We have not specified the geography we’re talking

about. Are we talking about the US only or is that a global market sizing question?

Answer: Let’s say it’s global. [STOP] if you’re practicing on your own, complete the next step (break down the problem) before continuing to read this guide.

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Step 2 – Break down the problem If you’re practicing on your own, put your structure in place, then compare it to the structure below and go through the explanation to understand how it

was developed. If your structure takes into account similar factors but is a bit different, then it works too.

If you’re playing the role of the interviewer, go through the candidate’s

structure and guide him or her as needed to ensure it’s close to the one below, unless it’s different but still works (takes into account the same factors but from a different angle).

Volume of commercial planes in the air now

Volume of opera�onal commercial planes

Yearly volume of commercial flights

Yearly volume of commercial travelers

Global popula�on

% financially capable

Probability of them being in the air now

Yearly volume of flights / plane

Avg. volume of travelers per plane

Avg. number of trips a year

We start by stripping out the “now” element from the main question. Similar to what we did for the previous case study, we first need to understand what

the total number of commercial planes is before we can apply the probability of “now.”

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To estimate the volume of commercial planes, we can either follow a supplyside approach (think of the number of airports globally, the average number of planes in each, etc.) or a demand-side approach (think of the number of

travelers, how many planes they need, etc.). Typically, the interviewee should

choose the approach they feel they’re more equipped for (they will have more data points to use as they back up their figures). Chances are that people

know more about traveling than they know about airports, so this settles it: demand-side approach.

Now, we start drilling down layer by layer: •

The volume of planes is nothing but the volume of flights divided by the

•

The volume of flights is the volume of repeat passengers divided by the

•

The volume of repeat passengers is the volume of travelers multiplied

average number of flights per plane.

average number of passengers per flight.

by the avg. number of trips they take a year, which depends on people’s

financial capability and interest in travel.

[STOP] if you’re practicing on your own, complete the next step (calculate) before continuing to read this guide. Keep in mind that your assumptions,

calculations and results in that next section can vary from mine and that’s

completely normal. I will be taking quick proxies in some cases and will not be justifying every single step to avoid overcrowding the book with details.

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Step 3 – Calculate

Volume of commercial planes in the air now

Volume of opera�onal commercial planes

Yearly volume of commercial flights

Yearly volume of commercial travelers

Global popula�on 8Bn

% financially capable 60%

Probability of them being in the air now 50%

Yearly volume of flights / plane 1.5k

Avg. volume of travelers per plane 150 Avg. number of trips a year 1.5

If you’re practicing on your own, compare your assumptions and calculations to the one below.

If you’re playing the role of the interviewer, guide the candidate as needed based on the below.

The calculation steps happen bottom-up (from the bottom of the tree to its top). This includes: •

Global population: This should be straightforward. The global population

•

Percentage of people who are financially capable: We can assume that it’s

is around 8 billion.

mostly the middle class and upper class individuals can afford to travel (~60% if we follow the Low:Middle:Upper ratio of 40%:35%:25%)

•

Avg. number of trips per year: As previously stated, we can’t just throw a 89

number (e.g., 3 trips). We need to relate to the wider set of travelers (e.g., some businessmen travel 4 times a month, some families travel once a year). If we assume that frequent travelers travel monthly (12 times a

year) while casual travelers (constituting the vast majority of travelers, or around 95% of them) travel once a year for their main vacation, we can derive that, on average, people take 1.5 trips a year (1x95% + 12x5%). •

Avg. volume of travelers per plane: When in doubt, refer back to a

personal experience. I know that, on average, when I go on planes, there

are roughly 25-35 rows with 4-6 seats each. This means that, on average,

planes can carry 150 passengers (30x5). •

The volume of yearly flights per plane: Assuming that each flight that

planes take is, on average, 3 hours and that the plane needs 2 hours of

prep before departure, this means that each trip is about 5 hours in total (3 in the air, 2 on the ground). This gives each plane the time to make 4-5 trips a day. We can assume 4 a day to stay conservative, with the

rest of the day used for maintenance. This means 4x365= Roughly 1.5K

flights a year.

The only assumption left for us to estimate is the probability of planes being in the air. Again, let’s take a more extended period of time: a whole day.

Doing 4 trips a day means 12 hours in the air (3x4) and another 12 on the

ground. So there is, in general, a 50% probability of being in the air (12/24).

[STOP] if you’re practicing on your own, complete the next step (consolidate) before continuing to read this guide.

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Step 4 – Consolidate

Volume of commercial planes in the air now 15k Volume of opera�onal commercial planes 31k Yearly volume of commercial flights 47Mn Yearly volume of commercial travelers 7Bn Global popula�on 8Bn

% financially capable 60%

Probability of them being in the air now 50%

Yearly volume of flights / plane 1.5k

Avg. volume of travelers per plane 150 Avg. number of trips a year 1.5

As we finalize the calculations, we’ll arrive at the final estimate that can be

synthesized top-down, starting from the answer and digging a little deeper into the layers.

A good wrap-up would be: “Based on various assumptions we discussed, it seems there could be roughly 15K commercial planes in the air as of now. We arrived at this number by

estimating the total number of commercial planes globally, which is around 31K and multiplying it by the probability of them being in the air, which is

50%. The number of planes was derived based on the number of flights, the

average volume of flights per plane, the average volume of travelers per plane, and taking into account demographics and behavioral segments such as financial capability.”

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C a s e s tu dy 3 HOW MANY BOTTLES OF WATER ARE SOLD EACH YEAR? Level: Medium Skills required: Standard market sizing Given: How many bottles of water are sold each year? [STOP] On the next page, you’ll find a guide to solving this case which includes the various steps provided below: Step 1 - Clarify the given

Step 2 - Break down the problem Step 3 - Calculate

Step 4 - Consolidate If you’re practicing on your own, make sure to only look at the part of the guide that is relevant to the step you’re currently at and only do so after

you’ve completed that step. For instance, ask yourself what questions you can ask to clarify the given, then look at step 1 in the guide before moving on to step 2.

For now, you can start by thinking of any clarifying question you would want to ask before moving on to the next page.

If you’re playing the role of the interviewer, go through the full guide first and use it to steer the candidate in the right direction across all the steps.

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B e g inn in g o f gui de Step 1 – Clarify the given You’ll find below a series of questions that could be asked to clarify the given before structuring the case.

If you’re practicing on your own, take a few minutes to compare these to the ones you had in mind.

If you’re playing the role of the interviewer, guide the interviewee with the below only if he/she asks. •

Define the “what”: By bottles of water, do we mean all sizes of bottles?

Answer: Small and large bottles are included. We can exclude gallons and

bigger containers. •

Define the “what”: By bottles of water, do we mean mineral water or would that include any other type of liquids?

Answer: Only mineral water. •

Define the “where”: We have not specified the geography we’re talking

about. Are we talking about the US only or is that a global market sizing question?

Answer: Let’s say global. [STOP] if you’re practicing on your own, complete the next step (break down the problem) before continuing to read this guide.

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Step 2 – Break down the problem If you’re practicing on your own, put your structure in place, then compare it to the structure below and go through the explanation to understand how it

was developed. If your structure takes into account similar factors but is a bit different, then it works too.

If you’re playing the role of the interviewer, go through the candidate’s

structure and guide him/her as needed to ensure it’s close to the one below, unless it’s different but still works (takes into account the same factors but from a different angle).

Volume of water bo�les sold/consumed each year

Volume consumed in households

Number of households consuming bo�led water

Total number of households with access to water

Avg., number of bo�les used per relevant household per year

Volume consumed outside households

Global popula�on with access to water

Avg., number of water bo�les consumed out of home per year

% consuming bo�led water

To estimate the volume of water bottles sold and consumed, it makes sense

to follow a demand-side approach relating back to our average consumption of water and how many of us there are.

Now, let’s start going top-down from the question itself into deeper layers. •

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First of all, we either consume bottled water at home or outside of our homes, meaning we can branch out the question as such.

•

To estimate the number of bottles consumed by/in households, we can take the total number of households with access to mineral water and divide it by their average yearly consumption.

•

The number of households consuming bottled water is just a portion of

•

On the out-of-home side, we can take an estimate on the number of

the wider volume of households with access to water.

bottles each of us consumes in the context of work, visits, etc., but that’s only occasional.

[STOP] if you’re practicing on your own, complete the next step (calculate) before continuing to read this guide. Keep in mind that your assumptions, calculations and results in that next section can vary from mine and that’s

completely normal. I will be taking quick proxies in some cases and will not be justifying every single step to avoid overcrowding the book with details.

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Step 3 – Calculate If you’re practicing on your own, compare your assumptions and calculations to the structure below.

If you’re playing the role of the interviewer, guide the candidate as needed based on the below.

We start bottom-up with the assumptions before we aggregate up (next stage). Here are the assumptions we need to estimate: •

Total number of households with access to water: Out of the global

population of 8Bn, around 1-2Bn don’t have access to water, at least not in standard forms such as water bottles (e.g., might be in bigger gallons at scale). This leaves us with 6Bn with an average household size of 3.

That’s our first assumption: 2Bn households with access to mineral water via standard forms. •

Percentage of these households that would consume bottled water

(as opposed to drinking from the tap, buying bigger gallons for water dispensers, etc.). We can assume that, in general, there are multiple options for households to choose from, maybe 4 of them (medium

water gallons, drinking from the tap in certain countries, large gallons for water dispensers, and large bottled water of 1.5-2L). Without

much information about the split of these 4, we can assume an equal probability across (25% for large bottles of water). We’ll also assume smaller bottles (