Today is Pi Day.

Pi Day is an annual celebration of the mathematical constant π (pi). Pi Day is observed on March 14 (the 3rd month) since 3, 1, and 4 are the first three significant figures of π, and was first celebrated in the United States.
In 1988, the earliest known official or large-scale celebration of Pi Day was organized by Larry Shaw at the San Francisco Exploratorium, where Shaw worked as a physicist, with staff and public marching around one of its circular spaces, then consuming 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 (111 H. Res. 224), recognizing March 14, 2009, as National Pi Day.
For Pi Day 2010, Google presented a Google Doodle celebrating the holiday, with the word Google laid over images of circles and pi symbols.
In the year 2015, March 14 was celebrated as "Super Pi Day". It had special significance, as the date is written as 3/14/15 in month/day/year format, or the first five digits of pi (3.1415). At 9:26:53, the date and time together
For the 30th anniversary in 2018, it was a Dominique Ansel pie with the circumference divided by its diameter.