Jean Prestet

Jean Prestet, who lived from 1648 to 1690, was a French Oratorian priest and mathematician who contributed to combinatorics and number theory. He grew up poor and as a teenager worked as a servant at the Oratory of Jesus in Paris, where he was promoted to secretary for Nicolas Malebranche, who taught him mathematics. From 1670 he wrote the textbook Elémens des Mathématiques under Malebranche's guidance, unusually focused on algebra alone because he believed algebra to be the most fundamental part of mathematics, with geometry merely applied algebra. It was published in 1675 by the Oratorian order for its colleges, contained a proof of Descartes' rule of signs that he later acknowledged to be incomplete and a generalisation of Euclid's lemma, and was used by Abraham de Moivre in an early attempt to teach himself mathematics. He was appointed to the mathematical chair at the University of Angers in 1681, and a revised edition of 1689 included early work on the fundamental theorem of arithmetic.