March 14 is National Pi Day. The one you use in math, not the one you eat.
(CNN) — Wednesday is National Pi Day, not the kind you eat — the kind you calculate.
The Greek letter π is the symbol used to represent the mathematical constant of 3.14. That’s the ratio of a circle’s circumference to its diameter.
Pi has been calculated to more than one trillion digits past its decimal point, but it can be calculated infinitely without creating any repetition or pattern.
It is celebrated on March 14th because the date’s numerical abbreviation is 3/14. Many people also celebrate the day by eating pies.