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 preparation efforts. Rather, you should work on your identified weaknesses – in this way your preparation will be a lot more efficient.
For the PST I would suggest the following approach:
- Try to find at least 5-6 practice cases online. There are several you can find for free, if needed you can purchase some
- Do one of the tests immediately to check your score. As the passing score is around 70% and you have 26 questions, you should target a final score around 18
- Look at the type of questions you made more mistakes with. Understand if mistakes are due to math issues. If so, try to identify a pattern for that (eg you are slow in divisions/percentages; you did not use correctly elimination approach, etc). Work on them accordingly. Then proceed doing regularly the other tests before your interview.
For cases, you can follow an equivalent approach:
- Practice math-intensive cases, doing both live practice and screening MBA handbooks and focusing on the math heavy cases
- Write down all the mistakes you regularly do
- Understand which is the common pattern in your mistakes (most commons: missing zeros, wrong graph reading, unstructured communication of math steps). Remember that in live cases your communication of the math steps is also important - you should align with the interviewer on the steps to follow
Having said that, you are expected to know the following/have the following knowledge in a consulting interview:
- Good mental math. You can practice on some of the online tools available on daily base to improve. It is better if you allocate a small amount of time daily then practice intensively few days only before the interview
- Rule of 72 and difference between simple and compound interest
- Ratios from 1/2 to 1/10
- Breakeven formula
- DCF formulas and perpetuity (here there is a link to a complete analysis of them - https://www.preplounge.com/en/consulting-forum/case-net-present-value-calculations-325)
GMAT practice can definitely be useful as a way to speed up your math, but will help to focus on specific parts of math preparation only. If you have communication problems for your math or graph interpretation issues, for example, you wont be able to fix them with GMAT practice. On the other hand, live feedback from a good partner could help to understand what you are doing wrong and improve accordingly.