Easy · Mental Math & Estimation · Numerical · ~2 min · #99

Digits in 99 to the 20th

Real interview · Jane Street

How many digits does $99^{20}$ have? Work it out without a calculator.

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Worked solution

Give the problem an honest attempt first, then reveal the full explanation.

Reported in interviews

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Candidate-reported and unverified; the firm may phrase it differently or no longer ask it. The wording here is our own paraphrase, and the solution was written and checked independently of any answers posted at the source.

Concepts

Order-of-magnitude estimation

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