|Significance||3, 1, and 4 are the three most significant figures of π|
|Celebrations||Pie eating, discussions about π|
|Next time||14 March 2015|
|Related to||Pi Approximation Day|
|Part of a series of articles on the|
|mathematical constant π|
Pi Day is an 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.
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 will occur on 3/14/15 at 9:26:53 following the sequence of pi.
The earliest known official or large-scale celebration of Pi Day was organized by Larry Shaw in 1988 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.
In the year 2015, Pi Day will have special significance on 3/14/15 at 9:26:53 a.m. and p.m., with the date and time representing the first 10 digits of π. That same second will also contain a precise instant corresponding to all of the digits of π. However, some argue that 9:26:54 a.m. and p.m. on 3/14/15 are more accurate because of the 11th digit of π being 5, which would cause the 10th digit to round up to 4.
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.
- Landau, Elizabeth (2010-03-12). "On Pi Day, one number 'reeks of mystery'", CNN. Retrieved on 2010-03-14 from http://www.cnn.com/2010/TECH/03/12/pi.day.math/index.html.
- United States. Cong. House. Supporting the designation of Pi Day, and for other purposes. 111th Cong. Library of Congress.
- "Pi Approximation Day is celebrated today.". Today In History. Verizon Foundation. Retrieved 2011-01-30.
- Berton, Justin (March 11, 2009). "Any way you slice it, pi's transcendental". San Francisco Chronicle. Retrieved 2011-03-18.
- Jonathan Borwein (10 March 2011). "The infinite appeal of pi". Australian Broadcasting Corporation. Retrieved 2011-03-13.
- Adrian Apollo (March 10, 2007). "A place where learning pi is a piece of cake". The Fresno Bee.
- "Exploratorium 22nd Annual Pi Day". Exploratorium. Retrieved 2011-01-31.
- McCullagh, Declan (March 11, 2009). "National Pi Day? Congress makes it official". Politics and Law (CNET News). Retrieved 2009-03-14.
- "Pi Day". Google Doodles. Google. Retrieved 2012-10-09.
- By Douglas Main (2014-03-14). "It's Not Just Pi Day, It's Pi Month! | Popular Science". Popsci.com. Retrieved 2014-07-22.
- "Pi Month Celebration & Circle of Discovery Award Presentation | College of Computer, Mathematical, and Natural Sciences". Cmns.umd.edu. 2014-03-11. Retrieved 2014-07-22.
- Ro, Sam (March 13, 2014). "March 14, 2015 Will Be A Once-In-A-Century Thrill For Math Geeks". Business Insider. Retrieved 13 March 2014.
- Rosenthal, Jeffrey S. (October 2014). "Pi Instant". Retrieved 23 October 2014.
- "Happy Pi Day". http://science.slashdot.org/comments.pl?sid=2036304&cid=35480022.
- "Honiton Community College Pi Day - Jazmin Year 9". YouTube. Retrieved 2013-07-22.
- "HCC Celebrate International Pi Day". Honitoncollege.devon.sch.uk. Retrieved 2013-07-22.
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- "Princeton Pi Day & Einstein Birthday Party". Princeton Regional Convention and Visitors Bureau. Retrieved 2013-03-14.
|Wikimedia Commons has media related to Pi Day.|
- Exploratorium's Pi Day Web Site
- NPR provides a "Pi Rap" audiovideo
- Pi Day
- Professor Lesser's Pi Day page