De occulta parte numerorum, quam algebram vocant, 1560
Born in Le Mans into a bourgeois family, he studied at the Collège de Navarre in Paris, where his brother Jean was a professor of mathematics and philosophy. He subsequently studied law and medicine, frequented the literary circle around Marguerite de Navarre and from 1541 to 1543 he was secretary to René du Bellay. In 1541 he published the first French translation of Horace's Ars Poetica and during this period he also published numerous scientific and mathematical treatises.
In the Renaissance, the French language had acquired many inconsistencies in spelling through attempts to model French words on their Latin roots (see Middle French). Pelletier tried to reform French spelling in his 1550 treatise Dialoguɇ Dɇ l’Ortografɇ e Prononciation Françoęſɇ ("Dialogue on French spelling and pronunciation"),[2] advocating a phonetic-based spelling using new typographic signs which he would continue to use in all his published works. In this system, he consistently spells his name with one "l": Iacquɇs Pɇlɇtier du Mans.
His last years were spent in travels to the Savoy, Germany, Switzerland, possibly Italy and various regions in France and in publishing numerous works in Latin on algebra, geometry and mathematics and medicine (including a refutation of Galen and a work on the plague). In 1572, he was briefly director of the College of Aquitaine in Bordeaux, but, bored by the position, he resigned. During this period, he was friends with Michel de Montaigne and Pierre de Brach. In 1579, he returned to Paris and was named director of the College of Le Mans. A final collection of poetry Louanges was published in 1581.
Pelletier died in Paris in July or August 1582.
New naming convention for large numbers
While maintaining the original system of the French mathematician Nicolas Chuquet (1484) for the names of large numbers, Jacques Pelletier promoted milliard for 1012 which had been used earlier by Budaeus. In the late 17th century, milliard was subsequently reduced to 109. This convention is used widely in long scale countries.
