Numbers have hidden patterns. Some numbers divide evenly into others. Some numbers cannot be broken down further. These patterns appear everywhere in programming, from hash tables to cryptography to game loops.
In this section, I will teach you divisibility rules, factors, multiples, and prime numbers. You will learn how to find all divisors of a number, test for primality, and use the Sieve of Eratosthenes to find all primes below n.
By the end, you will recognize divisibility patterns instantly and write efficient prime-finding algorithms.