Ronald Graham and Graham's Number

Ronald Graham was an American mathematician born on Halloween and was credited by the AMS as ``one of the principal architects of the rapid development worldwide of discrete mathematics in recent years''. Unfortunately, he passed away this summer. Graham was known for his many contributions to Graph theory, probability, and Ramsey theory, where Graham's number appears. In this talk, I'll discuss Graham's number, one of the largest numbers used in an actual math proof (sort of) and just how large it really is.