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

Other Ways to Honor the Same Number

March 14 isn’t the only option. Pi Approximation Day lands on July 22 — because 22/7 is the classic fraction approximation of pi, and written in day/month format, that’s 22/7. November 10 works too: it’s the 314th day of a non-leap year. Some people take their pi celebrations wherever they can get them.

And then there’s Tau Day, June 28. Tau — the ratio of a circle’s circumference to its radius — equals 2π, or roughly 6.28, making June 28 the obvious candidate. The unofficial tradition calls for double portions of pie. If you’re going to celebrate a number, celebrate it properly.