The Two Jugs Trick: How to Measure Exactly 4 Litres
A friendly look at the classic water jug puzzle, why pouring between a 5 litre and 3 litre jug lands on 4, and the number idea behind it.
Subject · 3 posts
number theory
How an Ancient Game Finds Hidden Prime Numbers
Cross out the multiples and the prime numbers are what survive, a simple two thousand year old trick you can try in a quick game.
The Number Theory You Actually Need
Sieves, greatest common divisors, modular arithmetic and inverses. Five tools, each about ten lines, that cover almost every number theory problem you will meet.
Problem Solving From Zero17