Jean Prestet

Jean Prestet was a French Oratorian priest and mathematician who contributed to combinatorics and number theory, born in 1648 and dying in 1690. He grew up poor, worked as a servant of the Oratory of Jesus in Paris as a teenager, and was promoted to secretary of Nicolas Malebranche, who taught him mathematics. In 1670, under Malebranche's guidance, he began the textbook Elémens des Mathématiques, which unusually focused exclusively on algebra, treating it as the most fundamental field and geometry as merely applied algebra. It contained a proof of Descartes's rule of signs that he later admitted was incomplete and a generalization of Euclid's lemma to non-prime divisors, and was published in 1675 for the Oratorian colleges. Abraham de Moivre used it in an early attempt to teach himself mathematics. Prestet became mathematics chair at Angers in 1681, and a revised edition of 1689 included early work on the fundamental theorem of arithmetic.