14 March 2015 :: Pi Day [ 14th of March ]
Pi Day is an American annual celebration commemorating the mathematical constant π (pi). Pi Day is observed on March 14 (or 3/14 in the month/day date format), since 3, 1, and 4 are the first three significant digits of π in decimal form. In 2009, the United States House of Representatives supported the designation of Pi Day. If the particular date existed, the holiday would be celebrated elsewhere on April 31, as America is the only country that uses the month-first date system.
Pi Approximation Day is observed on July 22 (or 22/7 in the day/month date format), since the fraction 22⁄7 is a common approximation of π, which is accurate to two decimal places and dates from Archimedes.
A sequential time occurs on 3/14/15 at 9:26:53.58979… following the sequence of pi to all digits, using the America-based system of dating.
Pi Day has been observed in many ways, including eating pie, throwing pies and discussing the significance of the number π. Some schools hold competitions as to which student can recall Pi to the highest number of decimal places.
Massachusetts Institute of Technology has often mailed its application decision letters to prospective students for delivery on Pi Day. Starting in 2012, MIT has announced it will post those decisions (privately) online on Pi Day at exactly 6:28 pm, which they have called “Tau Time”, to honor the rival numbers Pi and Tau equally.
The town of Princeton, New Jersey, hosts numerous events in a combined celebration of Pi Day and Albert Einstein’s birthday, which is also March 14. Einstein lived in Princeton for more than twenty years while working at the Institute for Advanced Study. In addition to pie eating and recitation contests, there is an annual Einstein look-alike contest.