Practice more problem-solving at https://brilliant.org/TedEd/
Solution to Bonus Riddle: https://brilliant.org/tededautobiographical/

You’ve found Leonardo da Vinci’s secret vault, secured by a series of combination locks. Fortunately, your treasure map has three codes: 1210, 3211000, and… hmm. The last one appears to be missing. Can you figure out the last number and open the vault? Tanya Khovanova shows how.

Lesson by Tanya Khovanova, directed by Artrake Studio.

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