Pi Day; π

Pi Day and Pi Approximation Day are two holidays held to celebrate the mathematical constant π (pi) (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.

Sometimes Pi Minute is also celebrated; this occurs on March 14 at 1:59 p.m. If π is truncated to seven decimal places, it becomes 3.1415926; making March 14 at 1:59:26 p.m., Pi Second (or sometimes March 14, 1592 at 6:53:58 a.m.).