Pierre de Fermat

French lawyer and magistrate at the Parlement of Toulouse who pursued mathematics as an amateur, corresponding with contemporaries such as Pascal and Mersenne rather than publishing formally. His work with Blaise Pascal on a gambling problem in 1654 is usually credited as founding probability theory, and Fermat's Little Theorem is still central to number theory and modern cryptography. He is best remembered for a note he wrote in the margin of his copy of Diophantus's Arithmetica around 1637, claiming to have a remarkable proof that no three positive integers can satisfy a to the n plus b to the n equals c to the n for any integer n greater than two, a proof he said the margin was too narrow to contain. No such proof was ever found among his papers, and the claim, Fermat's Last Theorem, went unproven for 358 years.