Do you celebrate Pi Day? Pi is an essential mathematical symbol, representing the ratio of a circle's circumference to its diameter. Coincidentally, pie, a delicious dessert usually made with a pastry crust and fruit filling, shares the same pronunciation. So someone came up with the brilliant idea to combine them and celebrate both on one day: March 14th, or 3/14 (which matches the first digits of pi). It's one of those rare holidays that can make math fun for anyone, whether you're the kind of person who's interested in a tart pastry or a juicy math problem. Not sure what I'm talking about? Just read (and watch!) on for more Pi Day fun.