Pierre de Fermat
Pierre de Fermat (; French: [pjɛʁ də fɛʁma]; 31 October 1605 – 12 January 1665) was a French magistrate, polymath, and above all, a mathematician who is given credit for early developments that led to infinitesimal calculus, including his technique of adequality. In particular, he is recognized for his discovery of an original method of finding the greatest and the smallest ordinates of curved lines, which is analogous to that of differential calculus, then unknown, and his research into number theory.