Yesterday would have been Paul Erdös’s 100th birthday. (It’s pronounced air-dish). Not only was Erdös an extremely prolific mathematician (he published over 1,500 papers), he was a fascinating and somewhat eccentric man. For the last few years of his life, he did not have a home; he travelled around and stayed with collaborators while working with them. He was a terrible houseguest, but his hosts were so honored to be working with him that they didn’t mind. Mathematicians sometimes refer to their Erdös number (sort of like a Kevin Bacon number for math). If you co-authored a paper with Erdös, you have an Erdös number of 1. If you co-authored a paper with someone who co-authored a paper with Erdös, you have an Erdös number of 2, and so on.
To learn more about this amazing man, I refer you to a Scientific American article, a segment from Radiolab, and a book (which the Scientific American and Radiolab stories use as the primary source).
Scientific American: An Arbitrary Number of Years Since Mathematician Paul Erdös’s Birth
Radiolab: From Benford to Erdös