Pi Day
Contents
English[edit]
Etymology[edit]
pi + day, from the date March 14th in the month/day format (that is, 3/14), 3, 1 and 4 being the first three significant digits of the mathematical constant π.
Pronunciation[edit]
 (Received Pronunciation, General American) IPA^{(key)}: /ˈpaɪ deɪ/
Proper noun[edit]
 March 14th, an annual celebration of the mathematical constant π (pi).

1997, Louise Bock; Susan Guengerich; Hope Martin, “March Celebrations”, in Multicultural Math Fun: Holidays around the Year, Portland, Me.: J. Weston Walch Publisher, ↑ISBN, page 83:
 Did you know that March 14 is Pi Day (no, π is not misspelled). Pi Day is celebrated on 3/14 or 3.14! To commemorate this remarkable ratio, we have a few circular activities. The first is the Pizza Survey. What are the students' favorite toppings on pizza? What do you like best?

1999, David H. Albert, “Exits and Entrances”, in And the Skylark Sings with Me: Adventures in Homeschooling and Communitybased Education, Gabriola Island, B.C.: New Society Publishers in cooperation with Holt Associates/Growing Without Schooling, ↑ISBN, page 128:
 As Quakers, we do not as a matter of religion celebrate any holidays (more accurately, all days are to be considered holidays because they have equal potential for revealing the Divine to us), but as a cultural matter we celebrate all kinds: Hindu, Christian, Jewish, ethnic, birthdays of famous composers, artists, writers, and scientists, π Day (March 14th – we bake several pies and divide them into fractions before eating), even some we just make up ourselves.

2002, Ivan Peterson, “A Passion for Pi”, in Mathematical Treks: From Surreal Numbers to Magic Circles (Spectrum Series; a Science News Book), [Washington, D.C.]: Mathematical Association of America, ↑ISBN, page 17:
 Of all known mathematical constants, however, pi continues to attract the most attention. […] The Exploratorium in San Francisco continues to celebrate Pi Day on March 14 each year, starting at 1:59 pm.

2009 March 12, H. Res. 224 Supporting the Designation of Pi Day, and for Other Purposes^{[1]}, [Washington, D.C.]: United States Government Publishing Office, archived from the original on 28 December 2016, page 2:
 Whereas Pi can be approximated as 3.14, and thus March 14, 2009, is an appropriate day for "National Pi Day": Now, therefore, be it / Resolved, That the [United States] House of Representatives— / (1) supports the designation of a "Pi Day" and its celebration around the world; […]

2012 June 19, Jonathan M[ichael] Borwein, “The Life of Pi: From Archimedes to Eniac and Beyond”, in David H[arold] Bailey; Jonathan M. Borwein, Pi: The Next Generation: A Sourcebook on the Recent History of Pi and Its Computation, Switzerland: Springer Nature, published 2016, DOI: , ↑ISBN, page 446:
 Likewise, March 14 in North America has been π Day, since in the USA the month is written before the day ('314'). In schools throughout North America, it has become a reason for mathematical projects, especially focussing on π.

2015 March 14, Sam Ro, “March 14, 2015 will be a onceinacentury thrill for math geeks”, in Business Insider^{[2]}, archived from the original on 4 March 2016:
 March 14, or 3/14, is recognized by math geeks as Pi day. That happens every year. But as UBS’s Art Cashin notes, next year’s Pi day will be a onceinacentury Pi day. “At 9:26:53 a.m., they can write 3/14/15; 9:26:53, which you should also recall are the first ten digits of Pi in perfect order,” said Cashin.

2016, Liz Strachan, “A Little More Pi”, in Easy as Pi: Maths Made Simple, London: Robinson, ↑ISBN:
 Pi lovers like to celebrate Pi Day every year. In the US, they write the date with the month first, then the day and year. So in 2015, 14th March was 3 14 15, the first five digits of π. So that was a really special Pi Day when, of course, they sang their special song, Pi, Pi, Mathematical Pi, to the tune of that great song everyone danced to in the 1970s, 'Byebye, Miss American Pie' by Don McLean.

Alternative forms[edit]
Translations[edit]
March 14th, an annual celebration of the mathematical constant π (pi)

