### π Pi Day π

Pi Day is an unofficial holiday commemorating the mathematical constant π (pi). 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. Pi is an unbroken string of digits that never repeats, never ends, and never starts becoming predictable.

On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution (HRES 224), recognizing March 14th, as National Pi Day in the United States. With the use of computers, Pi has been calculated to over 1 trillion digits past the decimal. Pi is an irrational and transcendental number meaning it will continue infinitely without repeating.

Pi Approximation Day is observed on July 22 (or 22/7 in day/month date format), since the fraction 22⁄7 is a common approximation of π.

Many people will toast to pi on 3/14 at 1:59 because the digits continue 3.14159.

Some celebrate a more specific time of 3/14 1:59 and 26.5 seconds.

People who would like to celebrate an even more specific time can celebrate on 3/14 1:59 and 26.5