'''Pi day''' is a [[holiday | "Holiday"holiday]] celebrating [[mathematics]].
Pi Day, a facetious holiday celebrating the mathematical constant [[Pi]] is observed on March 14. Celebrations often involve eating pie, cookies or some other spherical delicacy. The date comes from the first three digits of pi (3/14) (in american notation) with some people begin beginning their celebration at 1:59:26.5 (the following digits (3.14159265)). Many Elementary and Middle School teachers use March 14 to introduce their students to the concept of Pi
Pi Approximation day is a similar holiday, celebrated on July 22 (from the approximation 22/7).