Puzzles

Master Sun's mystery number

A pile of objects is counted out in groups. Counted three at a time, two are left over. Counted five at a time, three are left over. Counted seven at a time, two are left over. What is the smallest number of objects that fits all three counts?

Reveal the answer

23. This is Sun Zi's "problem of the unknown number of objects" from the Chinese text Sunzi Suanjing (Book III, Problem 26), compiled sometime between the 3rd and 5th centuries CE, the earliest known worked example of what mathematicians now call the Chinese Remainder Theorem.

Sun Zi (attributed; exact identity unknown), Sunzi Suanjing (The Mathematical Classic of Sun Zi) — c. 3rd-5th century CE, Book III, Problem 26

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