Math formulae

Question

Is there a list I can find somewhere for all the math formulae you need to know for cases? I see some variations in ROI formulae (some use Annual profit/Investment cost and others (Annual Profit - Investment cost)/Investment cost). What's the right formula? If there are some resources that can help with that'd be great.

Answer 1

Hi there,

100% Recommend Rocket Blocks.
Online "Drills": Preplounge has some
Math sheets (print these and do them on paper): Google "Math Drills"
In addition to that, you can ask other PrepLoungers to case you on math-heavy cases. You can also search for those case types here and work through them yourself.

Some key formulas/concepts:

Breakeven
NPV (with + without growth, perpituity + 1-2 years from now)
% Change
ROI
Margin
Markup
Inventory turnover

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Some great answers from a variety of angles have already been asked. Check these out!

Mental Math

https://www.preplounge.com/en/consulting-forum/mental-math-help-7962

https://www.preplounge.com/en/consulting-forum/is-quick-mental-math-a-skill-that-can-be-learned-5210

Conceptual/Contextual Math

https://www.preplounge.com/en/consulting-forum/materials-for-practicing-conceptual-case-math-8016

https://www.preplounge.com/en/consulting-forum/math-concepts-6951

Key Math Equations

https://www.preplounge.com/en/consulting-forum/math-equations-their-use-7934

Math Practice

https://www.preplounge.com/en/consulting-forum/case-math-practice-6877

Answer 2

Hi, I recommend look at the Bootcamp here in the platform, very insightful both for practicing and testing

Best,
Antonello

Answer 3

Hi there,

The formula for ROI is Net income from investment / Investment cost (equivalent to the first you mentioned). So if you buy something for 5 and resel it for 10, your ROI is:

(10-5)/5 = 100%

The most common formulas you need to know in a consulting interview are:

Breakeven
Rule of 72
Perpetuity formula and general NPV formula
ROI and related financial ratios

Besides that, you should be familiar with simple and compound interests.

Best,

Francesco

Answer 4

Hello!

Being 80-20, the ones you need are break even and NPV -both the normal one and in perpetuity-

Hope it helps!

Cheers,

Clara

Answer 5

Yes.

I've put one together that you can use as a sort of cheat sheet.

Cheatsheet: The Must-Know Consulting Terms for Interviews

Best,

Cristian

Answer 6

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AI and ChatGPT are definitely game-changers for consulting prep! They’re great for structuring case frameworks, generating potential interview questions, and even simulating cas... (read entire answer)