Triskaidekaphobia: fear of the number 13 If thirteen people sit down at a table, will one die within a year? Why did five U.S. presidents join the Thirteen Club? What is the only major New York hotel that has a thirteenth floor? In 13, a fascinating cultural history-cum-detective story, Nathaniel Lachenmeyer gets to the root of how one superstition—the fear of the number 13—developed among wildly divergent societies. A book about mythmaking, 13 explores why people believe what they believe, and the real reason Friday the 13th is the most unlucky day in the world.