Schedule mock interviews on the Meeting Board, join the latest community discussions in our Consulting Q&A and find like-minded Interview Partners to connect and practice with!
Back to overview

Can writing out calculations slow you down when taking PST and gmat style tests?

3
2.8k
8
Be the first to answer!
Nobody has responded to this question yet.
Top answer
on Sep 12, 2018
Ex-MBB, Experienced Hire; I will teach you not only the how, but also the why of case interviews

Can writing out calculations slow you down? Well, yes - of course! What will happen if you don't write it down however? Can you do the math in your head (or estimate it)? If so, don't write things down. If you can't, then you really only have two options: (1) your write the math down, "waste" a little bit of time, and have a chance to get to the right answer, or (2) you don't write it down, get the wrong answer, and never even get a chance to get an interview.

What you want to do it practice quick math enough that you have time to finish the whole test within the allocated time and with sufficient accuracy that your score helps you rather than hurts you. PrepLounge has good material, caseinterviewmath.com is a fantastic resource, and you will also find dozens of books on the suject at your local library, Barnes & Noble or Amazon. There's no shortcut, you will have to put in the work sorry.

Vlad
Coach
on Sep 12, 2018
McKinsey / Accenture Alum / Got all BIG3 offers / Harvard Business School

Hi,

I think the answer is in your question already. Here is how you can progress with mental / written math:

1) Learn how to multiply double digit numbers (https://www.youtube.com/watch?v=6ndkkPZYJHo).

2) Learn how to work with zeros. You've mentioned - always use 10^power instead of zeros

Example:

300x9000 = 3*10ˆ2 x 9*10ˆ3=3x9*10ˆ(2+3)=27*10ˆ5

Handwritten it looks not that complicated. If you get used to writing all the numbers that way, you will never loose zeros and all multiplications/divisions will be replaced with + or -.

3) Learn the division table up to 1/11 (i.e. 5/6 = 83.3%). It will help you calculate any percentage problems

Finally - practice a lot with the math tools (Preplounge, V. Cheng, Mimir Math)

Good luck!

edited on Sep 11, 2018

Hi, thank you both for taking the time to answer this for me. It has really helped me.  Patrick 

0
Similar Questions
Consulting
Why am I pretty great at Maths in Cases, but terrible at GMAT questions?
on Apr 26, 2025
Global
10
500+
Top answer by
Daniel
Coach
Ex-McKinsey, Bain & Kearney | 5+ yrs consulting, coaching & interviewing | 95%+ candidate success
22
10 Answers
500+ Views
+7
Consulting
What Bain HireVue MCQ test looks like? [SEA Region]
on Mar 13, 2025
Asia
4
500+
Top answer by
Mariana
Coach
Free CV evaluation | xMckinsey | 1.5h session | +200 sessions | Free 20-min introductory call
13
4 Answers
500+ Views
+1
Consulting
McKinsey, US- Interviewing process
on Apr 18, 2025
USA
10
300+
Top answer by
Hagen
Coach
#1 recommended coach | >95% success rate | 8+ years consulting, 8+ years coaching and 7+ years interviewing experience
11
10 Answers
300+ Views
+7