Paul Erdos was a Hungarian mathematician.
He is famous for having collaborated with many mathematicians in writing articles, hence the term "Erdos Number"; A mathematician who has published an article with Erdos is said to have an Erdos Number 1. One who has published with somebody who has published with Erdos is said to have a number 2 and so on.

He was a child prodigy, who could square a 3-digit number within a few seconds; He was a horrible guest, yet so many people offered hospitality to him; He couldn't stand talks about women ans sex, and used to call people who started them, "trivial"; He had his own lexicon -- Epsilon = child, boss = woman, poison = alcohol etc; He used to call colleagues at 3 AM to talk to them about a new mathematical idea he had; He could concentrate on many things simultaneously: Playing a game of chess, reading an encyclopedia of medicine and proving a theorem.


100 Themes Challenge -- Deep In Thought.