Fermat's Last Theorem

Pythagoras gave us 3² + 4² = 5² — infinitely many triples for n = 2. But what about n = 3? n = 4? In 1637, Pierre de Fermat scribbled in a book's margin that xⁿ + yⁿ = zⁿ has no positive integer solutions for any n > 2, adding 'I have discovered a truly marvelous proof of this, which this margin is too narrow to contain.' He never wrote it down. Three and a half centuries of the world's best mathematicians tried and failed — until Andrew Wiles, in secret for seven years, closed it in 1994.