Pi Day

Pi Day
Larry Shaw, the creator of Pi Day, at the Exploratorium
Observed by	Worldwide
Type	Secular
Significance	3, 1 and 4 are the three most significant figures of π
Date	March 14
Celebrations	Pie eating, discussions about π [1]
Related to	Pi Approximation Day

Part of a series of articles on
the mathematical constant π
Uses
Area of disk Circumference Use in other formulae
Properties
Irrationality Transcendence Less than 22/7
Value
Approximations Memorization
People
Archimedes Liu Hui Zu Chongzhi Madhava of Sangamagrama William Jones John Machin John Wrench Ludolph van Ceulen Aryabhata
History
Chronology Book
In culture
Legislation Holiday
Related topics
Squaring the circle Basel problem Tau (τ) Other topics related to π
v d e

Pi Day is a holiday commemorating the mathematical constant π (pi). Pi Day is celebrated on March 14 (or 3/14 in month/day date format), since 3, 1 and 4 are the three most significant digits of π in the decimal form. In 2009, the United States House of Representatives supported the designation of Pi Day.^[2]

Pi Approximation Day is held on July 22 (or 22/7 in day/month date format), since the fraction ²²⁄₇ is a common approximation of π.^[3]

History

Larry Shaw created Pi Day in 1988.^[4] The holiday was celebrated at the San Francisco Exploratorium, where Shaw worked as a physicist,^[5] with staff and public marching around one of its circular spaces, then consuming fruit pies.^[6] The Exploratorium continues to hold Pi Day celebrations.^[7]

On Pi Day 2004, Daniel Tammet recited 22,514 decimal digits of π.^[8]

On March 12, 2009, the U.S. House of Representatives passed a non-binding resolution (HRES 224),^[2] recognizing March 14, 2009, as National Pi Day.^[9]

For Pi Day 2010, Google presented a Google Doodle celebrating the holiday, with the word Google laid over images of circles and pi symbols.^[10]

At 9:26:53 on Pi Day 2015, the date will be 3/14/15 at 9:26:53, corresponding to 3.141592653.

Date abstractions from pi

Pi Day is observed on March 14 because of the date's representation as 3/14 in month/day date format. This representation adheres to the commonly used approximation of 3.14 for π.

The fractional approximation of π,²²⁄₇, resembles the date July 22 in the day/month format, where it is written 22/7. Pi Approximation Day is therefore celebrated on July 22.

Celebration

Pi Pie at Delft University.

There are many ways of celebrating Pi Day. Some of them include eating pie and discussing the relevance of π.^[1]

The Massachusetts Institute of Technology often mails its application decision letters to prospective students for delivery on Pi Day.^[11]

See also

• Mole Day
• Square Root Day

Notes

External links

Wikimedia Commons has media related to: Pi Day

• Official web site for Pi Day
• Exploratorium's Pi Day Web Site
• NPR provides a "Pi Rap" audiovideo
• Pi Day Activity - Memorizing Pi
• Pi Day Challenge - Students have fun with math and logic!
• piZone Pi education, history and activities including National Pi Day & Pi approximation day
• The Pi Searcher Search for arbitrary digits in Pi. Often updated with new features on Pi Day.
• "A Piece of Pi" Music based on Pi for violin composed for Pi Day to honor Math teachers.
• Website dedicated to the Number Pi.