
problem
Dirisibly yours
Find and explain a short and neat proof that 5^(2n+1) + 11^(2n+1) +
17^(2n+1) is divisible by 33 for every non negative integer n.
Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?
I'm thinking of a number. My number is both a multiple of 5 and a multiple of 6. What could my number be?