Diophantus writes the Arithmetica in 13 books (only 10 survive: 6 in Greek, 4 in Arabic rediscovered in 1968), a collection of 290 algebraic problems solved in rational numbers. He introduces for the first time a rudimentary symbolic notation for the unknown and its powers, separating mathematics from pure rhetoric. His indeterminate equations — 'Diophantine equations' — found modern number theory. Fermat writes in the margin of his copy of the Arithmetica (1637) the note that gives rise to Fermat's Last Theorem. Translated into Arabic by Qusta ibn Luqa (c. 870) and into Latin by Xylander (1575), it was rediscovered in Europe just before Viète and Descartes developed modern symbolic algebra.