Pi Day is an annual celebration of the mathematical constant π (pi). Pi Day is observed on March 14 (3/14 in the month/day format) since 3, 1, and 4 are the first three significant digits of π.^[2][3] In 2009, the United States House of Representatives supported the designation of Pi Day.^[4] UNESCO‘s 40th General Conference decided Pi Day as the International Day of Mathematics in November 2019.^[