Number Theory
Primes, modular arithmetic and famous problems.
Numbers
How Modular Arithmetic Works: Clocks, Remainders and Inverses
Learn modular arithmetic through clock examples, the congruence notation, modular inverses, Fermat's little theorem, and everyday uses like check digits.
NumbersHow the Sieve of Eratosthenes Finds Prime Numbers
Learn how the sieve of Eratosthenes lists all primes up to a limit by crossing out multiples, why it stops at the square root, and how fast it runs.