fstop / Getty

No one knows the origin of the dollar sign, but the U.S. Bureau of Engraving and Printing has a pretty good guess. The government agency responsible for designing and printing all those crisp dollar bills says the design, originally used to denote Spanish and Mexican pesos, "P S ," came to be written such that the S was on top of the the P. The symbol was widely used before the 1875 issue of the first U.S. paper dollar. And in case you never noticed, it doesn't actually appear on U.S. currency at all.

See TIME's "Top 10 Things You Didn't Know About the Penny."

Next You Can't Take It with You