Pierre de (pjɛr də). 1601--65, French mathematician, regarded as the founder of the modern theory of numbers. He studied the properties of whole numbers and, with Pascal, investigated the theory of probability
Fermat (fěr-mä') Pronunciation Key
French mathematician who is best known for his work on probability and on the properties of numbers. He formulated Fermat's last theorem, which remained unsolved for over three hundred years.