Pi Day is an annual celebration of the mathematical constant π (pi). Pi Day is observed on March 14 (the 3rd month) since 3, 1, and 4 are the first three significant figures of π. It was founded in 1988 by Larry Shaw, an employee of the San Francisco science museum, the Exploratorium. 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 July 22 (22/7 in the day/month format, an approximation of π) and June 28 (6.28, an approximation of 2π or tau).
Last Updated: March 10, 2024