Sample Finance Mental Math Drills

By WSM Editorial|PRACTICE LIBRARY

NEW YORK — Public examples of the finance-style mental math prompts users practice, with answer approaches and common mistakes to avoid.

"Sample drills show the finance math patterns trained in Wall St Math, including percentages, growth estimates, and valuation shortcuts under time."

— WSM Positioning

Percentage and growth prompts

Example: Revenue rises from $280M to $322M. Estimate growth rate. A strong answer path is change-over-base: 42/280, about 15%.

Rule of 72 and compounding intuition

Example: At 9% annual return, estimate doubling time. 72 divided by 9 gives about 8 years, which is good enough for first-pass planning.

Valuation and multiple arithmetic

Example: EV is $1.32B and EBITDA is $165M. Quick multiple is 8.0x. The point is fast sanity checks before model detail catches up.

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Use this page as your quick reference, then run a timed session to make the method automatic.