Thanks for the replies guys! I know (and use) caseinterviewmath.com as well. A good website indeed, but only for practicing. They don't provide "tips and tricks" on how to solve sums like the afore... (more)

# All questions tagged mental math - Consulting Q&A - PrepLounge.com

Ask a question## Math training - how do you do it?

## Tips to do big multiplications in my mind

Hi, Basically, you need to develop 3 calculation skills: 1) Learn how to multiply double digit numbers (google fast math tips or The Veda math). 2) Learn how to work with zeros. Best way - al... (more)

## Hi all - does anyone have any material to prep mental maths? Thanks a lot!

There are many sources u can use e.g. 1. Mental Maths Tool from Preplounge 2. Mental Maths Tool from Victor Cheng 3. GMAT Questions 4. IQ Test also include mental maths questions e.g. sol... (more)

## Division techniques

Hi, There are two techniques that you can use: 1) Learn how to work with zeros. Best way - always use 10^power instead of zeros Example: 300x9000 = 3*10ˆ2 x 9*10ˆ3=3x9*10ˆ(2+3)=27*10ˆ5... (more)

## Hi, what is the best way to brush up on quantitative skills for the Mckinsey PST and overall math calculations used during case interviews at Bain and Mckinsey? Thanks!

Hi, Here is how you can improve your math skills: 1) Fast math - train, train, and train again Learn how to multiply double digit numbers (https://www.youtube.com/watch?v=6ndkkPZYJHo... (more)

## Is there a trick to quickly estimate the average annual growth percentage / to or total compounded growth, without a calculator? i.e. X will grow with 5% for the coming 10 years.

Hi, You can use the rule of 72. For example, if you know the revenue will grow from 100M to 400M in 12 years and you need to know the CAGR: 100M will double and grow to 200M in 6 years C... (more)

## Enhancing skills for mental math

Hi, Here is how you can improve your math skills: 1) Mental math - train, train, and train again Learn how to multiply double digit numbers (https://www.youtube.com/watch?v=6ndkkPZYJ... (more)

## Calculations: When is an estimate not good enough?

Hi Anonymous, first of all, let me state that one result of proper case interview preparation will be that this question will become completely irrelevant to you. ALL calculations in Consulting cas... (more)

## When is it OK to estimate? Is a fast estimate better than a slow but accurate answer?

Hi, Ask the interviewer 1-2 times to get a sense of how comfortable he is with rounding numbers and how many zeroes he requires. Continue with an assumption that you should keep that level of... (more)

## Engaging the interviewer while doing math / figuring out an exhibit

Hi, For math you should: Present the interviewer your approach (formula, calculation steps, equation, etc) Check with him whether the approach is correct Start calculations Come back to... (more)