How to learn case interview by myself ?

case interview preparation
New answer on Aug 15, 2020
4 Answers
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Anonymous A asked on Dec 06, 2018

Hi everyone,

I'm going to prepare case interview. However, I want to learn it by myself first before reaching out for mock case in order not to waste time of my partner and save my resources also (money - because I'm currently a senior university student)

Therefore, could you please share with me your experience or process to prepare case interview by youself ?

Thank you so much,

P/s: I have already read basic materials such as Case In Point, Victor Cheng, MConsulting Prep.

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Anonymous B updated the answer on Dec 06, 2018


Let me start off by saying this: this is very doable, though you will hit the low ceiling of solo prep quickly. You can read the bootcamp material on this site. You can also watch YouTube videos from the firms themselves (e.g. Bain's videos) or case prep sites (e.g. PrepLounge, Consulting Confidant). Reenact the candidate's part, see what you miss out on.Think out loud. Pace yourself. Do Victor Cheng's LOMS. Most importantly, record your voice to see how you sound (to pay attention to your enunciation, verbosity, and eloquence).

I think you have effectively 6-8 hours of the solo prep above before plateauing.

Just a passing advice: worst case scenario, your partner will get to know what a bad performance looks like. Don't rid them of that blessing!

Best of luck!


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replied on Dec 06, 2018
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School


The earlier you start practicing with the partners - the better. I recommend the following approach:

1) Start with "Case in point" book - you can download this book for free everywhere. It's not the best guide on how you should approach the cases, however, it will give you the basic understanding.

2) Start practicing cases with partners here or find them locally. !!! Find experienced partners or coaches who can provide a good feedback!!!

3) Purchase and read Viktor Cheng Book (Amazon Kindle store) and listen to LOMS (his website). I recommend to reread the book and listen to LOMS every 15 cases.Every time, having more experience, you’ll be finding something new.

4) Practice fast math

  • Learn how to multiply double digit numbers (
  • Learn the division table up to 1/11 (i.e. 5/6 = 83.3)
  • Learn how to work with zeros (Hint: 4000000 = 4*10ˆ6)
  • Use math tools (Mimir math for iOS), Math tool on Viktor Cheng website to practice

5) Below you can find a list of the most common case types and some high-level recommendations on structuring:

  • Market sizing - structuring from the supply or demand side. Structuring using a formula or using an issue tree
  • Profitability - basic profitability framework. Remember about different revenue streams and product mix
  • Market context cases (Market Entry, New product, Acquisition, etc). Always start with the big picture "market". Finish with something specific to the case (e.g. How to enter?"). Structure it as if you are defining the work streams for the real project.
  • Operational math problem (e.g. Should we increase the speed of an elevator or just buy a second one? How should we reduce the queues? Etc.) - Structuring as a process / value chain, with inflows, operations, and outflows
  • Cost cutting - I provided the recommendations on structuring it here:
  • Valuation - Purely financial structure with cash flows, growth rate, WACC / hurdle rate, etc.
  • Synergies - revenue synergies (price, qty, mix) and cost synergies (value chain).
  • Social / economics cases (e.g. How to improve the quality of life in the city? How to increase the revenues of the museum?) - huge variability. Practice 3-5 social cases before the interview

6) Also, I would try to focus on the most common industries in the following priority(sorted by probability of getting a case): 1-retail and CPG; 2-airlines; 3-Telecom; 4-banking; 5-natural resources; 6-tech

7) ! Important: don't forget about the FIT interview part. Crafting you stories and backups stories will require a couple of weeks!


Here is a good list of articles regarding the different parts of the case:

1) Start with clarifying questions:

2) Communicating while structuring. Here is a long post by me on how to communicate the structure during the case study:

3) Using hypothesis. I made a post about hypothesis here:

4) Communicating while making calculations:

  • Always tell the interviewer your approach
  • Check with the interviewer that your approach is correct
  • Come to the interviewer with some preliminary answers
  • Check your assumptions with the interviewer

5) Communicating during the analysis of graphs / tables

  • Take a minute to look at the graph. Read the graph title. Look at the graph type and define the type (pie chart, line chart, etc). Look at the legend (ask for clarifying questions if necessary). Identify whats going on on the graph. Look for: Trends, % structures. Look for unusual things - correlations, outliers,
  • Make 3-4 conclusions from the graph. Think out loud on potential hypothesis on what could be the root cause / what are the consequences
  • Prioritize the most important for your current analysis and move forward with the case

6) Communicating while answering questions on creativity

  • Ask an interview for a minute to think
  • Think of several buckets of ideas (e.g. organic growth / non-organic growth / differentiation). Remember to think as big as possible
  • Narrow down to each bucket and generate as many ideas as possible
  • Present the structure (buckets) and then your ideas

7) Communicating your conclusion. You can find a good example I've posted here:

8) Communicating your FIT stories

Use the top-down approach while communicating your stories. "The Pyramid Principle" is the must-read by ex McKinsey on this topic.

I recommend using the STAR framework:

  • In Situation, you should briefly provide the context, usually in 1 or 2 sentences
  • Task usually includes 2 or 3 sentences describing the problem and your objective.
  • Then you provide a list of specific actions you took to achieve the goal. It should take 1 or 2 sentences per action (Usually 3-4 actions). Note that the interviewer can stop you any minute and ask for more details.
  • The results part should have 1 or 2 sentences describing the outcomes. This part is finalizing your story - make sure it can impress the interviewer and stay in the memory.


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replied on Dec 08, 2018
Ex-MBB, Experienced Hire; I will teach you not only the how, but also the why of case interviews

I am a little late to the party, but here are some of my thoughts:

1. Is it possible? Of course!

2. Is it likely? No, but neither is getting in to MBB with coaches: there are so many qualified applicants that admission is always a long shot

3. Is it best practice? No

4. Ok, you still want to go it alone. What next?

4a. First, you need to learn the case mechanics, understand what good looks like and what bad looks like. There's plenty of free material on the web, including here on PrepLounge and on Victor Cheng's; he also has a great 6 hours of free video on YouTube btw

4b. Second, you need to get someone who can give you the relevant constructive feedback. Perhaps your spouse, best friend or roommate - or perhaps fellow candidates like yourself. In my experience, that won't be easy and you need to be lucky, but not impossible either

4c. Third, you need to heed that feedback and actually implement it as you keep doing cases; your partner will have to call you out on it when you fail, which you will from time to time

4d. Fourth, you will probably need to practice even more than you would with a coach. Why? Because on average, the feedback will not be as targeted and as actionable as the one we'd give you. Why? because we know what to look for, and are learned to communicate it in a way that helps you. Anyboday can tall you that you are bad, few can explain why and how to do better... and keep you motivated

Parting thoughts: I am vehemently against Case In Point, at least as far as the case frameworks are concerned; please don't waste your time and ignore the bood. Case cracking isn't rocket science, no need to go all fancy. You do need a solid dose of realisem and business sense however, coupled with good logic and quick mental math. Luck always plays a role also. Focus on what you can control, and prepare as best as you can. A good coach will help you do that - don't make it harder on yourself to save a few hundred bucks when the payout will be in the tens or hundreds of thousands over the course of your career.

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Anonymous replied on Aug 15, 2020

Dear A,

Here are some recommendations on how you can prepare for an interview!

You should practice mental calculation daily (percentages, decimal places, large numbers, arithmetic) – even though it's not the most important part of the interview and it's allowed to make mistakes, you need to master your numbers very comfortably.

Do as many cases as you can. After you gather a bit of experience of practicing with your fellow students, try to find a person who is now working or has worked in the past at the MBB's recruiting and ask them to simulate an interview with you. Or book a coaching session here on Preplounge.

Prepare and practice personal fit interviews – they are as important as the cases. Write down your stories, practice telling them with your fellow students, or with an expert (again, here on Preplounge)

Be aware of your mental state – try not to stress too much before and during the interview (I know it's easier said than done). Do sports, take care of your health, try yoga, meditation – whatever makes you less stressed. I've seen so many candidates pale as a sheet of paper during my time as an interviewer at McKinsey, all worried and jittery – as you can imagine this doesn't help your performance.

Good luck! DM me if you want to discuss it in more detail!



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