You Can Approximate Pi by Dropping Needles on the Floor

Who needs a supercomputer when you can calculate pi with a box of sewing needles? Happy Pi Day! March 14 is the date that otherwise rational people celebrate this irrational number, because 3/14 contains the first three digits of pi. And hey, pi deserves a day. By definition, it's the ratio of the circumference and diameter of a circle, but it shows up in all kinds of places that seem to have nothing to do with circles, from music to quantum mechanics. Pi is an infinitely long decimal number that never repeats.