I really like this puzzle. Obvious and so simple in retrospect.
Originally shared by Larry Phillips
A Bit of Number Theory
Choose any prime number p that is larger than 3. Compute p^2 – 1. The result is always divisible by 12.
Examples:
5^2 – 1 = 24 = 12 * 2
13^2 – 1 = 168 = 12 * 14
67^2 – 1 = 4488 = 12 * 374
Why is this true?
#mathematics
The result is even divisible by 24! (edit: by that, I don’t mean “24 factorial”)