396-314 B.C.

Greek mathematician and philosopher who wrote 70 works, of which only the titles remain. A student of Plato, Xenocrates was head of the Academy from 339 until his death. He tried to organize and popularize Plato's ideas, but understood them differently than others at the Academy. He wrote two mathematical works, On Numbers and The Theory of Numbers, and supposedly calculated the total number of syllables that can be made from the letters of the Greek alphabet at 1,002,000,000,000.