Number Theory Level 1: Factors and Primes

Why can 12 sweets be shared fairly in so many ways, but 13 in none? This course looks closely at whole numbers: how they are built by multiplying, how to test in a second whether one number divides another, and why the prime numbers are the atoms every other number is made of. You will meet numbers that make squares and triangles, multiply a number by itself again and again, find out when two buses meet again, and add fractions with different bottoms. At the end you will see your first real proofs - why something is true for every number, not just the ones you checked - why the primes never run out, how they keep messages safe on the internet, and questions about them that nobody has answered yet. Every idea is shown with dots and pictures, no letters, for anyone who has read Numbers Level 1.