Pi Day

Pi Day is an annual celebration of the mathematical constant

π

{\displaystyle \pi }

(pi) with events mostly in the United States. Pi Day is observed on March 14 (the 3rd month) since 3, 1, and 4 are the first three significant figures of

π

{\displaystyle \pi }

and was founded in 1988 by Larry Shaw, an employee of the Exploratorium, a science museum in San Francisco.

Celebrations often involve eating pie or holding pi recitation competitions. In 2009, the United States House of Representatives supported the designation of Pi Day. UNESCO's 40th General Conference designated Pi Day as the International Day of Mathematics in November 2019.

Other dates when people celebrate pi include Pi Approximation Day on July 22 (22/7 in the day/month format), an approximation of

π

{\displaystyle \pi }

; and June 28 (6.28), an approximation of 2

π

{\displaystyle \pi }

or

τ

{\displaystyle \tau }

(tau).

History

In 1988, the earliest known official or large-scale celebration of Pi Day was organized by Larry Shaw at the San Francisco Exploratorium, where Shaw worked as a physicist, with staff and public marching around one of its circular spaces, then consuming fruit pies. The Exploratorium continues to hold Pi Day celebrations.

On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution (111 H. Res. 224), recognizing March 14, 2009, as National Pi Day.