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Talk through the problem while you code. Signed-in reps become prep memory for the next session.
Multiply Strings
Multiply Strings is a great reminder that off-by-one errors love strings. Interviewers love it because it reveals your rule-based parsing and your edge-case discipline. The trap is hidden edge cases—empty input, repeated characters, and boundary indexing.
Learn this pattern
Math & Geometry Problems
Interview math problems test a small set of number-theory tricks: modular arithmetic, GCD/LCM, fast exponentiation, and sieve of Eratosthenes. Recognizing which trick applies is the hard part -- the implementation is short.
Meet your coaches
Talk through the problem while you code. Signed-in reps become prep memory for the next session.
Chat with Fin or Coco right now on mobile.
Start talking through the problem here. Switch to desktop when you're ready to code and run tests.
Start coaching sessionStart a coached rep now. Sign in before or after the session so StrongYes can save what you struggled with to your prep memory.
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Desktop required
Sorry - mobile cannot run the editor and tests yet. Use the next step below or email yourself a link to continue on desktop.
Math & Geometry Problems gives you a useful next rep while you are still on your phone.