Today is March 14th (3/14) and is celebrated as Pi Day since 3, 1, and 4 are the three most significant digits of π in the decimal form.
The first Pi Day was observed on this date in 1988 at the San Francisco Exploratorium when physicist Larry Shaw organized the Exploratorium staff and public to march around one of its circular spaces and then consume fruit pies. The Exploratorium continues to hold Pi Day celebrations. On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution (HRES 224), recognizing March 14, 2009, as National Pi Day. 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 to see which student can recall Pi to the highest number of decimal places; quite a feat since there over one trillion calculated digits after the decimal point.