SCIENCEThe Irrational Number That Somehow Became the World’s Most Beloved Holiday4 min read

The Pizza Deal Nobody Argues With

Pi has nothing inherently to do with the pie you eat — except that pies are circular, which is close enough for marketing purposes. Every March 14, restaurants across the country run specials built around the number 3.14. Whole pizzas for $3.14. Discounted slices of cherry pie. 7-Eleven, CiCi’s Pizza, and the Honey Baked Ham Company have all gotten in on the tradition at various points.

It’s a strange little commercial ecosystem built entirely around an infinite number. Nobody complains.

Congress Got Involved

By 2009, Pi Day had grown large enough to attract congressional attention. On March 12 of that year, the U.S. House of Representatives passed a non-binding resolution supporting “the designation of a Pi Day and its celebration around the world.” The Association for Competitive Technology and the American Chemical Society backed the measure — a rare moment of math advocacy on Capitol Hill.

UNESCO added its own endorsement, designating March 14 as the International Day of Mathematics. A number with no end somehow became a date on the global calendar.