Finance Interview Mental Math Practice

By WSM Editorial|How should you prepare mental math for finance interviews?

"Finance interview prep should combine timed arithmetic, structured explanations, and error-tracking so you stay accurate while speaking under stress."

— WSM Direct Answer

Why This Matters in Finance

Interviewers often assess both numerical control and communication clarity. Good candidates explain assumptions quickly while delivering answers at a practical pace.

Worked Examples

EXAMPLE 01

A stock rises 12% then falls 12%. Is it back to start?

▸ No, it is slightly below start.

Apply sequential math: 1.12 x 0.88 = 0.9856, so roughly -1.44% net.

EXAMPLE 02

Company revenue is $520M with 35% gross margin. Gross profit?

▸ About $182M.

Thirty percent is 156 and five percent is 26. Add to 182.

EXAMPLE 03

At 9x EBITDA and $70M EBITDA, what EV do you estimate?

▸ About $630M.