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)

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

Ask a question## Tips to do big multiplications in my mind

## Math training - how do you do it?

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)

## 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 Anonymous, in general the best way to improve your math is to first identify your weak points, then work accordingly on them. That’s because “generally” prepare for math won’t optimize your prep... (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)

Hi guys! Just wondering if anyone has tried the FastMath Ace the Case course, and can give feedba... (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)

## 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)

## How to divide and multiple thousands, milions and bilions fast?

Hi, There are several 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*10ˆ... (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)

## Times Tables 20-99

Hi Anonymous, my advice here: do NOT do such calculations in your head during an interview! You will not get ANY bonus points for this! The only two things that count are (1) You are consistently co... (more)

## Percentage Math Practice

Hi Mark, I am not sure I understand your challenge. Performing this kind of calculations will already give you the percentage, just expressed as a decimal figure (0,625 or 62,5% in your above example... (more)

## Slow in parsing and digesting Math word problems at case interviews - how to improve?

Hi, Something that helped my candidates - download ALL casebooks available online and go through the math problems in the cases. They will give a good sense of required business terminology. Then y... (more)

## How to calculate a market sizing case instinctively and quickly?

Hi, As for structuring - I've answered here: https://www.preplounge.com/en/consulting-forum/how-to-structuring-the-market-sizing-case-2301 For math skills you need to learn: Rounding u... (more)

## Any tips on how to calculate

Another little tip is to practice with multiplications, rather than divisions. It seems to be easier on the brain. E.g. 30% of 7 is easier done this way: 1) 7 x 30 = 210 2) Divide by 100.

## Where can I find this fraction decimal table?

Hi there, I quickly created a table for you in Excel - please see below :)

## Mental Math Skills

Hi A, Download mental math for your Iphone and practice everyday at least 10 min. All the best, Egor

## It is a silly question - but, What's the role of mental math & brain teasers in interviews?

On a related note: I have always had very positive feedback from interviewers when I told them that I already knew the answer to a given brainteaser, instead of pretending to solve it right then a... (more)