Number Theory

Explore the properties of whole numbers. Sieve out the primes, step through the Euclidean algorithm, and see modular arithmetic as a clock.

Key concepts

Numbers greater than 1 whose only divisors are 1 and themselves, the building blocks of every integer

When one integer divides another exactly, and how to find common divisors

Arithmetic that wraps around after reaching a modulus, like the hours on a clock

Cryptography, hashing and checksums all rely on number theory

Find every prime up to n by crossing out multiples step by step

Compute the GCD with repeated division, shown as tiling a rectangle with squares

Visualize addition and multiplication mod n on a clock and as times-table patterns