Pi Day is celebrated on March 14th (3/14) around the world.

Pi (often represented by the lower-case Greek letter π), one of the most well-known mathematical constants, is the ratio of a circle’s circumference to its diameter.  For any circle, the distance around the edge is a little more than three times the distance across.

Every year on March 14 - Albert Einstein’s birthday - number lovers can raise a piece of pie to Pi (π) Day, an international celebration of one of math’s most famous constants: the irrational, never-ending number π, pronounced pi (3.141592 . . .)