cannonball problem

Meaning

Proper Noun

• The challenge of proving that the only solution of the Diophantine equation :$\backslash sum\_\{n=1\}^\{N\}\; n^2\; =\; M^2\backslash ;$ with N > 1 is when N = 24 and M = 70.

Origin

• It can be visualized as the problem of taking a square arrangement of cannonballs on the ground and building a square pyramid out of them.