Improving math in McKinsey cases

MBB McKinsey
New answer on Aug 29, 2020
5 Answers
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Anonymous A asked on Feb 02, 2020

Hi all,

I've done a few of real McKinsey cases and I need to improve my math in them. The problem isn't in the calculations, it is in understanding what I need to do. How can I improve that?

I know that McKinsey math is text heavy and weird and once I understand what I need to do, the math becomes really easy, but how can I improve on "understanding" what needs to be done is my problem.

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replied on Feb 02, 2020
I am here to get you an offer! | Got 8 offers including the 3 MBBs and non MBB like Wyman, Roland Berger, Strategy&.

Hello Anonymous,
Thanks for sharing your question. Here are a few tips about improving your math skills:
1. Structuring the problem as a formula / An issue tree: for each math question, you need to ask yourself a. what are the drivers of the question (eg if it is a market sizing: market size = number of people x market share x number of items pp and then you deep dive into each driver)
2. Translating the formula and identify the driver in the indication of your interviewer: usually they will give you several indications and you need to link them to your initial formula or adapt your formula to the indications given to you
3. Stress-test your formula
4. calculate and take a step back: you need to test your result (too big, too small, comparable)
I hope that helps
Please reach out to me if you have other questions,

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Content Creator
replied on Feb 03, 2020
#1 Coach for Sessions (4.000+) | 1.400+ 5-Star Reviews | Proven Success (➡ | Ex BCG | 9Y+ Coaching

Hi Anonymous,

in general I would recommend the following steps for math in the

  1. Repeat the question – candidates sometimes do mistakes answering the wrong question in the math part
  2. Present how you would like to proceed from a theoretical point of view (you may ask for time before presenting if you initially don't know how to approach the problem)
  3. Ask for time and perform the first computations
  4. Present interim steps to the interviewer to keep him/her aligned – don’t just say the final number
  5. Continue with the computations until you find the final answer
  6. Propose next steps on the basis of the results you found

It seems your issues are mainly on point 2. If that’s the case, as Vlad mentioned I would recommend using the math part in casebooks as a way to improve on the identification of the formulas.

Hope this helps,


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Anonymous replied on Aug 29, 2020
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Content Creator
replied on Feb 02, 2020
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School


What has proving really useful to my candidates:

  1. Find all available casebooks online (20-30 casebooks)
  2. Go through each case, but just concentrate on solving the math problem
  3. You are prepared!

The reason is - there is a finite number of math problems that you can have in the case and most of them are in casebooks

And here is how to approach charts:

  1. Ask the interviewer for a minute to analyze the chart / table

  2. In your mind formulate the question you have to answer

  3. Look at the chart and define the type (pie chart, line chart, etc). Read the chart title. Read the legend

  4. Analyze the chart / table. Look for: Trends, comparisons, % shares, etc. Look for unusual things (consultants love to integrate these traps in charts) - correlations, outliers, etc

  5. Ask clarifying questions if required

  6. Provide your conclusion. You should not just describe the chart but also derive the conclusions. There should be at least one major conclusion plus any additional conclusions you can make. You can also provide your hypothesis on what can be the root causes / consequences

  7. Based on the interviewer's feedback, prioritize the most important information and define the next steps.

Here are some tips on how you can master that skill:

  1. Read "Say it with Charts" book by Gene Zelazny

  2. Check the chapters on cases with charts in the following case books "Consulting Bible" and "Vault guide for consulting"

  3. Refresh the basic statistics (Most of GMAT prep handbooks have a good summary)

  4. Practice GMAT Integrated Reasoning part (GMAT Official guide or Manhattan prep)

  5. Practice on real MBB presentations. Look at the chart, derive the conclusions, and compare it to the ones on the slide. Best sources to find presentations - various reports and articles on MBB websites, Slideshare


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Content Creator
replied on Feb 02, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


Do you mean business cases, or do you mean the McK initial test?


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Norah gave the best answer


I am here to get you an offer! | Got 8 offers including the 3 MBBs and non MBB like Wyman, Roland Berger, Strategy&.
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