March 14, written out as 3/14 in the US and a few other countries, is π day, as those are the first three digits of the famous number. π is one of the most important and fascinating numbers in math.

On March 14, math aficionados like myself celebrate Pi Day — the number that represents the ratio of a circle’s circumference ...

Thursday, March 14 (3/14) is National Pi Day. It’s a time to celebrate the number that represents the ratio of a circle's circumference to its diameter, and is often written as 3.14. It’s also ...