Pi, Greek letter (π), is the symbol for the ratio of the circumference of a circle to its diameter. Pi Day is celebrated by math enthusiasts around the world on March 14th. (in the mm/dd date notation: 3/14); since 3, 1 and 4 are the first three digits of π. March 14 is also the birthday of Albert Einstein and the two events are sometimes celebrated together. Pi = 3.1415926535…
