The integers from the ground up: divisibility, primes, gcd and the Euclidean algorithm, modular arithmetic, bases, Diophantine equations, Fermat and Euler, arithmetic functions, the Chinese remainder theorem, and orders.
11 topics · 45 lessons about 20 hoursBefore this: Pre-Algebra
What you'll be able to do
Prove divisibility facts from definitions
Compute with congruences, inverses and big powers
Solve linear and factorable Diophantine equations
Use Fermat, Euler, CRT and orders on contest problems
Start the course
Go through each topic step by step — prose, worked examples, quick checks, and a timed practice round after every section.