Pierre de Fermat

Pierre de Fermat was a French lawyer and mathematician who made foundational contributions to number theory while pursuing mathematics as an amateur alongside his career as a judge. He is best known for what became known as Fermat's Last Theorem, a claim he wrote in the margin of a book around 1637 stating that no three positive integers can satisfy the equation a to the n power plus b to the n power equals c to the n power for any integer n greater than two, a claim he stated he had a proof for that would not fit in the margin, and which was not proved by anyone else until 1994. Fermat also corresponded with Blaise Pascal in the 1650s on problems concerning games of chance, an exchange now regarded as a founding contribution to the mathematical theory of probability, and he independently developed methods anticipating differential calculus, including a technique for finding the maxima and minima of curves. His formulation of the principle of least time in optics, stating that light travels between two points along the path that takes the least time, also remains a standard part of the foundations of optics.