euclid

1 free lesson tagged euclid across Math. Each one is a short sequence of focused steps with narration and a five-question quiz at the end — take them in any order, no signup required.

Math

intermediate

Modular Arithmetic: Doing Maths on a Clock

Wrap the number line into a circle and addition and multiplication survive intact while division mostly does not. This lesson builds congruences, shows why you can reduce early to avoid overflow, works through Euclid's algorithm and modular inverses, and explains how a million-digit exponent becomes twenty multiplications.

10 steps·~15 min

Modular Arithmetic: Doing Maths on a Clock

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