Login
Login

Pi Day#Alternative dates

{{Short description|Annual mathematical celebration on March 14}}

{{Distinguish|National Pie Day}}

{{Use American English|date=July 2022}}

{{Use mdy dates|date=March 2024}}

{{Infobox holiday

| holiday_name = Pi Day

| image = Larry Shaw, the founder of Pi Day, at the Exploratorium in San Francisco--2007 March 21.jpg

| caption = Larry Shaw, the organizer of the first Pi Day celebration, at the Exploratorium in San Francisco

| observedby = United States

| significance = 3, 1, and 4 are the three most significant figures of {{pi}} in its decimal representation.

| duration = 1 day

| frequency = Annual

| scheduling = same day each year

| date = March 14

| mdy = y

| firsttime = 1988

| celebrations = Pie eating, pi memorization competitions, discussions about {{pi}}{{Cite news |last=Landau |first=Elizabeth |author-link=Elizabeth Landau |date=March 12, 2010 |title=On Pi Day, one number 'reeks of mystery' |language=en |publisher=CNN |url=http://www.cnn.com/2010/TECH/03/12/pi.day.math/index.html |access-date=March 14, 2018}}

| relatedto = Pi Approximation Day

| type = default

| longtype = Mathematical

}}

{{Pi box}}

Pi Day is an annual celebration of the mathematical constant {{pi}} (pi). Pi Day is observed on March 14 (the 3rd month) since 3, 1, and 4 are the first three significant figures of {{pi}}, and was first celebrated in the United States.{{Cite web |last=Bellos |first=Alex |date=March 14, 2015 |title=Pi Day 2015: a sweet treat for maths fans |url=https://www.theguardian.com/science/2015/mar/13/pi-day-celebration-maths-fans-language-memory-contests |access-date=March 14, 2016 |website=The Guardian}}{{Cite web |date=March 14, 2015 |title=Nedräkning mot internationella Pi-dagen |language=sv |url=http://sverigesradio.se/sida/avsnitt/514543?programid=412 |website=Swedish national radio company}} It was founded in 1988 by Larry Shaw, an employee of a science museum in San Francisco, the Exploratorium. Celebrations often involve eating pie or holding pi recitation competitions. In 2009, the United States House of Representatives supported the designation of Pi Day.United States. Cong. House. Supporting the designation of Pi Day, and for other purposes. 111th Cong. [http://thomas.loc.gov/cgi-bin/query/z?c111:H.RES.224: Library of Congress] {{Webarchive|url=https://web.archive.org/web/20090807131531/http://thomas.loc.gov/cgi-bin/query/z?c111:H.RES.224: |date=August 7, 2009 }} UNESCO's 40th General Conference designated Pi Day as the International Day of Mathematics in November 2019.{{Cite web |date=March 4, 2020 |title=International Day of Mathematics |url=https://en.unesco.org/commemorations/mathematics |website=UNESCO |language=en}}{{Cite journal |last=Rousseau |first=Christiane |url=https://www.ams.org/journals/notices/201908/rnoti-p1306.pdf |title=International Day of Mathematics |date=September 1, 2019 |journal=Notices of the American Mathematical Society |volume=66 |page=1 |doi=10.1090/noti1928 |doi-access=free |issue=8}}

Other dates when people celebrate pi include Pi Approximation Day on July 22 (22/7 in the day/month format), another approximation of {{pi}}; and June 28 (6.28), an approximation of 2{{pi}} or {{tau}} (tau).

History

In 1988, the earliest known official or large-scale celebration of Pi Day was organized by Larry Shaw at the San Francisco Exploratorium,{{Cite web |last=Berton |first=Justin |date=March 11, 2009 |title=Any way you slice it, pi's transcendental |url=https://www.sfgate.com/science/article/Any-way-you-slice-it-pi-s-transcendental-3169091.php |access-date=March 18, 2011 |website=San Francisco Chronicle}} where Shaw worked as a physicist,{{Cite web |last=Borwein |first=Jonathan |author-link=Jonathan Borwein |date=March 10, 2011 |title=The infinite appeal of pi |url=http://www.abc.net.au/science/articles/2011/03/10/3158045.htm?site=science/opinion |access-date=March 13, 2011 |publisher=Australian Broadcasting Corporation}} with staff and public marching around one of its circular spaces, then consuming fruit pies.{{Cite news |last=Apollo |first=Adrian |date=March 10, 2007 |title=A place where learning pi is a piece of cake |work=The Fresno Bee |url=http://apollotutoring.com/pi_day.pdf}} The Exploratorium continues to hold Pi Day celebrations.{{Cite web |title=Exploratorium 22nd Annual Pi Day |url=http://www.exploratorium.edu/pi/index.html |url-status=dead |archive-url=https://web.archive.org/web/20110314012746/http://www.exploratorium.edu/pi/index.html |archive-date=March 14, 2011 |access-date=January 31, 2011 |publisher=Exploratorium}}

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.{{Cite news |last=McCullagh |first=Declan |date=March 11, 2009 |title=National Pi Day? Congress makes it official |work=Politics and Law |publisher=CNET News |url=http://news.cnet.com/8301-13578_3-10194354-38.html?part=rss&subj=news&tag=2547-1_3-0-5 |access-date=March 14, 2009}} For Pi Day 2010, Google presented a Google Doodle celebrating the holiday, with the word Google laid over images of circles and pi symbols;{{Cite web |title=Pi Day |url=https://doodles.google/doodle/pi-day/ |access-date=October 9, 2012 |website=Google Doodles}} and for the 30th anniversary in 2018, it was a Dominique Ansel pie with the circumference divided by its diameter.{{Cite web |title=30th Anniversary of Pi Day! |url=https://doodles.google/doodle/30th-anniversary-of-pi-day/ |access-date=March 19, 2018 |website=www.google.com |language=en}}

Some observed the entire month of March 2014 (3/14) as "Pi Month".{{Cite magazine |last=Main |first=Douglas |date=March 14, 2014 |title=It's Not Just Pi Day, It's Pi Month! |url=http://www.popsci.com/article/science/its-not-just-pi-day-its-pi-month |magazine=Popular Science |access-date=July 22, 2014}}{{Cite web |date=March 11, 2014 |title=Pi Month Celebration & Circle of Discovery Award Presentation | College of Computer, Mathematical, and Natural Sciences |work=College of Computer, Mathematical, and Natural Sciences |url=http://cmns.umd.edu/news-events/events/1774 |access-date=July 22, 2014 |publisher=Cmns.umd.edu |author1=Jencasa }} In the year 2015, March 14 was celebrated as "Super Pi Day".{{Cite web |last=Mack |first=Eric |date=March 14, 2015 |title=Celebrate The Only Super Pi Day Of The Century |url=https://www.forbes.com/sites/ericmack/2015/03/14/happy-super-pi-day-heres-how-to-celebrate/ |access-date=March 14, 2019 |website=Forbes |language=en}} It had special significance, as the date is written as 3/14/15 in month/day/year format. At 9:26:53, the date and time together represented the first ten digits of {{pi}},{{Cite web |last=Ro |first=Sam |date=March 13, 2014 |title=March 14, 2015 Will Be A Once-In-A-Century Thrill For Math Geeks |url=http://www.businessinsider.com/pi-day-2015-2014-3 |access-date=March 13, 2014 |website=Business Insider}} and later that second, "Pi Instant" represented all of {{pi}}'s digits.{{Cite journal |last=Rosenthal |first=Jeffrey S. |url=http://probability.ca/jeff/writing/PiInstant.html |title=Pi Instant |date=February 2015 |journal=Math Horizons |volume=22 |page=22 |doi=10.4169/mathhorizons.22.3.22 |issue=3 |s2cid=218542599|url-access=subscription }}

Observance

Image:Happy Pi Day sign for sales on pies at Delicious Orchards.jpg, a country food market in Colts Neck, New Jersey]]

Pi Day has been observed in many ways, including eating pie, throwing pies and discussing the significance of the number {{pi}}.{{cite news|url=https://apnews.com/article/pi-day-celebration-math-infinite-number-f426c8659529cb07655b5f07b99ce1dd|title=What's Pi Day all about? Math, science, pies and more|first=Curt|last=Anderson|work=Associated Press|date=March 14, 2024|access-date=March 14, 2025|archive-url=https://web.archive.org/web/20240314074455/https://apnews.com/article/pi-day-celebration-math-infinite-number-f426c8659529cb07655b5f07b99ce1dd|archive-date=March 14, 2024|url-status=live}} The first two are due to a pun based on the words "pi" and "pie" being homophones in English ({{IPAc-en|pron|p|aɪ}}), and the coincidental circular shape of many pies.{{Cite web |last=Smith |first=K.N. |title=Wednesday's Google Doodle Celebrates Pi Day |url=https://www.forbes.com/sites/kionasmith/2018/03/14/wednesdays-google-doodle-celebrates-pi-day/ |website=Forbes}} Many pizza and pie restaurants offer discounts, deals, and free products on Pi Day.{{Cite news |last= |date=March 13, 2021 |title=Celebrate Pi Day With These Deals Around North Texas |work=NBC DFW |url=https://www.nbcdfw.com/news/local/celebrate-pi-day-with-these-deals-around-north-texas/2578077/ |access-date=May 14, 2022}} Also, some schools hold competitions as to which student can recall pi to the highest number of decimal places.{{Cite web |title=Honiton Community College Pi Day – Jazmin Year 9 |url=http://www.youtube.com/watch?v=dfM1i9_Un_Y) |url-status=dead |archive-url=https://web.archive.org/web/20131017125801/http://www.youtube.com/watch?v=dfM1i9_Un_Y |archive-date=October 17, 2013 |access-date=July 22, 2013 |publisher=YouTube}}{{Cite web |title=HCC Celebrate International Pi Day |url=http://www.honitoncollege.devon.sch.uk/index.php/about-honiton-community-college/10-honiton-community-college-news/146-hcc-international-pi-day-champions |url-status=dead |archive-url=https://web.archive.org/web/20140222033538/http://www.honitoncollege.devon.sch.uk/index.php/about-honiton-community-college/10-honiton-community-college-news/146-hcc-international-pi-day-champions |archive-date=February 22, 2014 |access-date=July 22, 2013 |publisher=Honitoncollege.devon.sch.uk}}

The Massachusetts Institute of Technology has often mailed its application decision letters to prospective students for delivery on Pi Day.{{Cite news |last=McClan |first=Erin |date=March 14, 2007 |title=Pi fans meet March 14 (3.14, get it?) |publisher=NBC News |url=http://www.nbcnews.com/id/17605924 |archive-url=https://web.archive.org/web/20130927144029/http://www.nbcnews.com/id/17605924/ |url-status=dead |archive-date=September 27, 2013 |access-date=January 24, 2008}} 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.{{Cite web |title=I have SMASHING news! |date=March 7, 2012 |url=http://mitadmissions.org/blogs/entry/i-have-smashing-news |access-date=March 12, 2012 |publisher=MIT Admissions}}{{Cite web |last=McGann |first=Matt |title=Pi Day, Tau Time |date=March 13, 2012 |url=http://mitadmissions.org/blogs/entry/pi-day-tau-time |access-date=March 18, 2012 |publisher=MIT Admissions}} In 2015, the regular decisions were put online at 9:26 am, following that year's "pi minute",{{Cite web |title=Keep your eyes to the skies this Pi Day |date=March 6, 2015 |url=http://mitadmissions.org/blogs/entry/keep-your-eyes-to-the-skies |access-date=March 14, 2018 |publisher=MIT Admissions |language=en}} and in 2020, regular decisions were released at 1:59 pm, making the first six digits of pi.{{Cite web |title=[Pinned] This is the way...to check your decisions |url=https://mitadmissions.org/blogs/entry/this-is-the-way-to-check-your-decisions/ |access-date=March 14, 2020 |website=MIT Admissions |date=March 10, 2020 |language=en-US}}

Princeton, New Jersey, hosts numerous events in a combined celebration of Pi Day and Albert Einstein's birthday, which is also March 14.{{Cite web |title=Princeton Pi Day & Einstein Birthday Party |url=https://www.visitprinceton.org/events/annual-events/pi-day/ |access-date=February 9, 2019 |website=Princeton Regional Convention and Visitors Bureau}} 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.

In 2024, the recreational mathematician Matt Parker and a team of hundreds of volunteers at City of London School spent six days calculating 139 correct digits of pi by hand, in what Parker claimed was "the biggest hand calculation in a century".{{cite AV media |people=Matt Parker |date=13 March 2024 |title=The biggest hand calculation in a century! [Pi Day 2024] |type=video |url=https://www.youtube.com/watch?v=LIg-6glbLkU |access-date=1 July 2024 |via=YouTube |location=London}}{{Citation|url=https://tomrocksmaths.com/2024/04/04/carnival-of-mathematics-226/|title=Carnival of Mathematics 226|first=Tom|last=Crawford|publisher=The Aperiodical|date=4 April 2024|access-date=30 August 2024|archive-url=https://web.archive.org/web/20240830074418/https://tomrocksmaths.com/2024/04/04/carnival-of-mathematics-226/|archive-date=30 August 2024|url-status=live}} On 15 August 2024, the main-belt asteroid 314159 Mattparker{{Efn|314159 are the first six digits of Pi.}} was named in his honor. The citation highlights Parker's biennial "Pi Day challenges", stating that they have helped to popularize mathematics.{{cite journal |url=https://www.wgsbn-iau.org/files/Bulletins/V004/WGSBNBull_V004_011.pdf#page=20 |author=International Astronomical Union |title=New Names of Minor Planets |journal=WGSBN Bulletin |volume=4 |number=11 |date=15 August 2024 |access-date=15 August 2024 |quote=Matthew Thomas Parker (b. 1980) is an Australian recreational mathematician, author, and science communicator based in the United Kingdom. His “Stand-up Maths” YouTube channel has gained more than one million subscribers. Parker's Pi Day (March 14) challenges, where he calculates (by hand) π with the help of volunteers, have popularized mathematics.}}{{cite news |url=https://www.theguardian.com/science/blog/2011/mar/14/pi-day |title=Pi Day: Help yourself to a slice of infinite, transcendental pi |first=Matt |last=Parker |date=14 March 2011 |access-date=15 August 2024 |work=The Guardian |archive-url=https://web.archive.org/web/20231019161621/https://www.theguardian.com/science/blog/2011/mar/14/pi-day |archive-date=19 October 2023 |url-status=live}}

Alternative dates

Pi Day is frequently observed on March 14 (3/14 in the month/day date format), but related celebrations have been held on alternative dates.

Pi Approximation Day is observed on July 22 (22/7 in the day/month date format), since the fraction {{frac|22|7}} is a common approximation of {{pi}}, which is accurate to two decimal places and dates from Archimedes.{{Cite web |title=Pi Approximation Day is celebrated today |url=http://www.thinkfinity.org/2010-07-22_pi-approximation-day |archive-url=https://web.archive.org/web/20101201010400/http://www.thinkfinity.org/2010-07-22_pi-approximation-day |archive-date=December 1, 2010 |access-date=January 30, 2011 |website=Today in History |publisher=Verizon Foundation}} In Indonesia, a country that uses the DD/MM/YYYY date format, some people celebrate Pi Day every July 22.{{Cite book |last=Purworini |first=D. |title=Pi Day celebration by local scientists in Indonesia |year=2016 |volume=7 |location=Anak Sudarti Foundation Bulletin |pages=7–8}}

Tau Day, also known as Two-Pi Day,{{Cite web |url=https://newsroom.lamresearch.com/Celebrating-Pi-Day-2017-and-More |title=Celebrating Pi Day 2017… and More! |first=Elizabeth |last=Pavel |date=March 13, 2017 |publisher=Lam Research |access-date=6 November 2024 |archive-url=https://web.archive.org/web/20230330164730/http://newsroom.lamresearch.com/Celebrating-Pi-Day-2017-and-More |archive-date=March 30, 2023 |url-status=live}} is observed on June 28 (6/28 in the month/day format).{{Cite web |title=Tau Day: Why you should eat twice the pie |url=https://lightyears.blogs.cnn.com/2012/06/28/tau-day-why-you-should-eat-twice-the-pie/ |url-status=dead |archive-url=https://web.archive.org/web/20130112211136/http://lightyears.blogs.cnn.com/2012/06/28/tau-day-why-you-should-eat-twice-the-pie/ |archive-date=January 12, 2013}} The number {{tau}}, denoted by the Greek letter tau, is the ratio of a circle's circumference to its radius; it equals 2{{pi}}, a common multiple in mathematical formulae, and approximately equals 6.28. Some have argued that {{tau}} is the clearer and more fundamental constant and that Tau Day should be celebrated alongside or instead of Pi Day.{{Cite news |date=March 13, 2018 |title=It's Pi Day today. But these people say we should refuse to celebrate it |language=en-GB |work=The Independent |url=https://www.independent.co.uk/news/science/pi-day-march-14-maths-google-doodle-pie-baking-celebrate-30-anniversary-a8254036.html |url-status=live |url-access=subscription |access-date=March 14, 2018 |archive-url=https://ghostarchive.org/archive/20220526/https://www.independent.co.uk/news/science/pi-day-march-14-maths-google-doodle-pie-baking-celebrate-30-anniversary-a8254036.html |archive-date=May 26, 2022}}{{Cite news |date=March 14, 2013 |title=Pi Day Turns 25: Why We Celebrate an Irrational Number |url=https://news.nationalgeographic.com/news/2013/03/031314-pi-day-exploratorium-mathematics-pie-science/ |archive-url=https://web.archive.org/web/20130314185319/http://news.nationalgeographic.com/news/2013/03/031314-pi-day-exploratorium-mathematics-pie-science/ |url-status=dead |archive-date=March 14, 2013 |access-date=March 14, 2018}}{{Cite web |last=BMJ |date=June 22, 2018 |title=Jeffrey Aronson: When I use a word ... The Days of Pi |url=https://blogs.bmj.com/bmj/2018/06/22/jeffrey-aronson-when-i-use-a-word-the-days-of-pi/ |access-date=May 2, 2023 |website=The BMJ |language=en-US}} Celebrants of this date jokingly suggest eating "twice the pie".{{Cite book |last=Bartholomew |first=Randyn Charles |url=https://www.scientificamerican.com/article/let-s-use-tau-it-s-easier-than-pi/ |title=Why Tau Trumps Pi |language=en}}{{Cite news |last=Landau |first=Elizabeth |title=In case Pi Day wasn't enough, it's now 'Tau Day' on the Internet |language=en |work=CNN |url=http://www.cnn.com/2011/TECH/innovation/06/28/tau.day.math/index.html}}{{Cite web |title=Tau Day – Come Eat Twice the (Pi)e |url=https://www.geocaching.com/geocache/GC56WHN_tau-day-come-eat-twice-the-pie?guid=19c50aa3-fe1c-4961-8df8-f03f3798de91 |language=en}}

Some also celebrate {{pi}} on November 10, since it is the 314th day of the year (in leap years, on November 9).{{Cite web |title=Pi Day – Fun Holiday |url=https://www.timeanddate.com/holidays/fun/pi-day |access-date=March 13, 2022 |publisher=Timeanddate.com}}

Gallery

File:Pi pie2.jpg|Pi Pie at Delft University

File:Pi day sale.jpg|A grocery store selling pies for $3.14 on Pi Day

File:Cremepiday.png|Creme pie in celebration of Pi day showing the Greek letter and the first digits of Pi.

See also

Notes

{{Notelist}}

References

{{reflist}}

External links

{{Commons category|Pi Day}}

{{Wiktionary|Pi Day}}

  • [http://www.exploratorium.edu/pi/ Exploratorium's Pi Day Web Site]
  • [https://www.idm314.org Official website of the International Day of Mathematics]
  • [https://en.unesco.org/commemorations/mathematics UNESCO page on the International Day of Mathematics]
  • [https://www.npr.org/sections/thetwo-way/2010/03/pi_day.html/ NPR provides a "Pi Rap" audiovideo]
  • [http://www.idm314.org/ Pi Day]
  • [http://www.math.utep.edu/Faculty/lesser/piday.html Professor Lesser's Pi Day page]
  • [https://www.eeo.cn/webcast.php?courseKey=8a44be5970c129ba 数学漫谈] (A Tour of Mathematics), a public lecture (in Chinese) delivered by Professor [http://lsec.cc.ac.cn/~yyx/ Ya-xiang Yuan] (President of International Council for Industrial and Applied Mathematics) on 14 March 2020, the first International Day of Mathematics ([https://web.archive.org/web/20210706210819/ftp://lsec.cc.ac.cn/pub/home/yyx/2020.03.14.15.pdf slides])

{{Science commemorative events|state=collapsed}}

{{authority control}}

Category:1988 establishments in California

Category:March observances

Category:July observances

Category:Observances about science

Category:Pi

Category:Recurring events established in 1988

Category:Unofficial observances