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# McKinsey Interview Prep: formula cheat sheet ?

Actively preparing for interviews with McKinsey Case Interview McKinsey
New answer on Jul 27, 2023
6 Answers
3.9 k Views

Hello all,

As I am preparing for my McKinsey interviews, are there any formula “cheat sheets” available to become more familiar with useful formulas to use during the case interview, etc?

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There is no one formula cheat sheet. The entire point is to have you prepare for a new type of problem in an interview. Practice is key, and the following are some mathematical concepts that would be helpful to have.

• Interest rates
• Compound margin
• NPV
• CAGR
• The "Rule of 72"

Additionally, practice the following to ensure efficiency and ease:

• Fast multiplication, especially for larger numbers
• Multiplication tables up to 15
• Fast division
• Order of magnitude calculations
• Ratios/Proportions
• Profit/Breakeven

Best,

Udayan

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Consulting math in general is really quite simple in terms of “formulas”. It´s just a matter of dealing with the stress when, let´s say, subtracting two large numbers with appropriate rounding and keeping track of decimal places.

What you will need is two things:

• Practice structuring i.e. establishing your “own formulas” based on the case problem. It´s all basic arithmetic but still plenty of ways to go wrong with too little practice
• Practice your consulting/mental maths (plenty of tools online) and learn how to communicate clearly your approach as you´re executing

Hope this helps, best of luck!

(edited)

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Hey there,

My suggestion would be to practice case math drills and keep notes on the different formulas you encounter. At a certain point, you will see how they are used and repeated across cases.

That way you learn and internalize formulas and their practical application rather than learning formulas by heart without context.

The outcome will be significantly different.

Cheers,

Florian

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Hello!

Precisely for the high amount of questions (1) asked by my coachees and students and (2) present in this Q&A, I created the “Economic and Financial concepts for MBB interviews”, recently published in PrepLounge’s shop (https://www.preplounge.com/en/shop/prep-guide/economic_and_financial_concepts_for_mbb_interviews).

After +5 years of candidate coaching and university teaching, and after having seen hundreds of cases, I realized that the economic-related knowledge needed to master case interviews is not much, and not complex. However, you need to know where to focus! Hence, I created the guide that I wish I could have had, summarizing the most important economic and financial concepts needed to solve consulting cases, combining key concepts theorical reviews and a hands-on methodology with examples and ad-hoc practice cases.

It focuses on 4 core topics, divided in chapters (each of them ranked in scale of importance, to help you maximize your time in short preparations):

• Economic concepts: Profitability equation, Break even, Valuation methods (economic, market and asset), Payback period, NPV and IRR, + 3 practice cases to put it all together in a practical way.
• Financial concepts: Balance sheet, Income statement/P&L and Performance ratios (based on sales and based on investment), +1 practice case
• Market structure & pricing: Market types, Perfect competition markets (demand and supply), Willingness to pay, Pricing approaches, Market segmentation and Price elasticity of demand, +1 practice case
• Marketing and Customer Acquisition: Sales funnel, Key marketing metrics (CAC and CLV) and Churn, +1 practice case

Feel free to PM me for disccount codes for the guide, and I hope it helps you rock your interviews!

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Hi there,

Absolutely! I provide a math sheet for all of my candidates when I create their tailored preparation plan. Feel free to shoot me a message!

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Hi!

I'm not sure what formulas you're referring to.

There are several articles here on PrepLounge on Consulting Maths - have a look at them and check if you can find your answer.

Hope this helps.

Best,

Anto

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Hi there,

If I were you I'd rather not become dependent on any cheat sheets. They became a crutch instead of an aid. After a few dozen cases you have a good control over most problem types. Then I'd use fast math exercises like the ones on PrepLounge or https://arithmetic.zetamac.com/ to increase your computational speed.

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Udayan gave the best answer
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