McKinsey / Accenture / Got all BIG3 offers / More than 300 real MBB cases / Harvard Business School
Book a coaching

Math for case interviews


I was just curious to know what kinds of math and algebra one should know for case interviews? The online web practice sites that randomize numbers are useful for helping you improve multiplication, addition, division, and so forth, but I am wondering what you might need to know beyond those basic. Everyone says that all you need for interviews is "back of the envelope" math, but I find that a bit misleading, as I've done fairly complicated practice problems on McK PST practice tests.

In other words, what kinds of math, besides the back of the envelope stuff, should one know and practice when preparing for case interviews?



  • Upvotes
  • Date ascending
  • Date descending
Vlad replied on 12/01/2017
McKinsey / Accenture / Got all BIG3 offers / More than 300 real MBB cases / Harvard Business School


Here is a set of things you need to know:

1) Math and formulas:

  • Interest rates calculations
  • Compound margin
  • NPV using the Rule of 72, Perperuity
  • CAGR using the Rule of 72
  • Currencies exchange calculations
  • Speed, time, distance calculations
  • Equations, systems of equations
  • Ratio & Proportions
  • Solving the problems by calculating the area of the triangle
  • Profit / breakeven formula
  • Correlations, outliers (being able to spot on the graphs, tables)

2) Fast math skills

  • Rounding up and down
  • Learn how to multiply double digit numbers (google fast math tips)
  • 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

3) Working with tables and graphs and deriving conclusions

  • Study "Say it with Charts" book
  • Check all available MBB presentations and publications. Practice to derive conclusions and check yourself with the actual ones from the article / presentation
  • GMAT IR part (Official guide and Manhattan prep)
  • Learn basic statistics (Any GMAT or MBA prep guides)

Good luck!

Paul replied on 12/03/2017

Hi everyone,

Thanks for the replies. I guess I am talking about the kind of math beyond the basics and I think some good things have been mentioned. The reason I ask is that I was recently viewing a case on YouTube and the interviewee had a bunch of information and he just threw it out hastily in an algebraic formula, which I didn't understand. Cheng's site is great for improving your skills and I've seen a dramatic improvement in my skills since I've started using it. However, I can't help but feel that there is a good deal of math beyond this level that should also be known and I am not exactly sure how to go about preparing for these (algebra, percentages, fractions, probability, etc.). The concepts like NPV, ROI, and so on are fairly straightforward, but these more fundamental math problems are what has been causing me concern.

Thanks all

Francesco replied on 12/01/2017
Ex BCG | MBB Specialist | #1 Expert for coaching sessions (1400+) and recommendation rate (100%)

Hi Paul,

I agree that in consulting interviews you will have to deal with basic math only (the most complicated thing could probably be a discounted cash flow computation).

The most important thing in preparation would be not to prepare on simple math only, but on math with time pressure (eg doing exercises with a timer with a strict time constraint for each question). Many candidates do mistakes in areas they would not have any problem to deal with without pressure due to the fact they trained on math only, and not on math under pressure.



Anonymous A replied on 11/30/2017


For interviews, basics maths is required. Let's break it into two different cateogry. Precise and Estimation with 20% accuracy. The math in both the categories remains same- addition, subtraction, divisiono and multiplication. However, it depends on the context what sort of answer is required, either precise or 20% close.

You can practice it on this platform or headover to Vcitor Cheng's website for free tool. That should suffice it.


Related BootCamp article(s)

Getting Up to Speed

In order to repeatedly demonstrate prerequisite skills under the pressure of a real case interview, you need to learn the basics and practice cases.

3 Comment(s)

Fast Math: How to Master Mental Math

Apply these tips and tricks for outstanding mental math shortcuts to impress your interviewer in your next case interview.

0 Comment(s)