While sequential dates are appealing to number nuts and the superstitious, March 14 takes date-play a step further. The month and day (3/14) that represent the ratio of the circumference of a circle to its diameter (3.14) has become an annual celebration of all things pi. That's right, Pi Day.
The first widely-attended Pi Day celebration was organized in 1988 by physicist Larry Shaw, also known as the Prince of Pi, at the San Francisco Exploratorium. It has become a yearly tradition that includes pi activities, a circular procession (a pi parade, if you will), and then, naturally, the eating of pie. In March 2009, the U.S. House of Representatives made it official when it passed a non-binding resolution (HRES 224) recognizing March 14 as National Pi Day.
So in celebration of the mathematical constant with a cult following, we are pleased to present some of the odder facts about 3.14.
1. Some people’s obsession with pi is nearly as infinite as the constant itself
As an irrational and transcendental number, pi will continue infinitely without repetition or pattern. It has even been calculated to a new world record of 31 trillion digits. Emma Haruka Iwao, a Google employee, used the company's cloud computing service to derive the number. It took Iwao 121 days using 25 virtual machines and 170 TB of data. This discovery makes number enthusiasts very excited.
While mere math mortals know pi as 3.14159, some super pi zealots memorize the value of pi to tens of thousands of digits. According to the Pi World Ranking List, Chao Lu holds the world record with his recital of 67,890 digits.
2. Rivers bend to pi
The way a river meanders is described by its sinuosity; the length of its winding path divided by the distance from the source to the ocean as measured in a straight line. Strange as it may be, the average river has a sinuosity of around 3.14, according to the journal Science.
3. Pi is irrational and transcendental
For those who are drawn to complicated partners, pi – which is classified as both irrational and transcendental – is for you! Pi is known as an irrational number because it can’t be written as a ratio or simple fraction; while 22/7 is close, it is not exact. It is also a transcendental number, meaning that it is not algebraic – it's not a root of a non-constant polynomial equation with rational coefficients.
For a translation of that last sentence, let Australia's Numeracy Ambassador, Simon Pampena, explain:
4. Before Watergate, there was (almost) Pi-gate
In 1897, the Indiana General Assembly nearly passed a bill adopting 3.2 as the exact value of pi at the behest of an amateur mathematician. Fortunately, a savvy math man from Purdue University, who was by chance visiting the legislature, intervened and prevented the bill from becoming law.
5. The freaky realization that pi is pie
Everybody has a good time making homophone jokes about pi and pie; it’s why pie is the unofficial foodstuff of Pi Day. But consider this (cue "Twilight Zone" theme): 3.14 seen in a mirror reads PIE.
6. Pi inspires
In Greek mythology, Euterpe may have been the muse of music, but for some math-loving musicians, pi serves to inspire. Austin-based musician Michael John Blake, for example, created the musical representation of pi (video below) to 31 decimal places at 157 beats per minute (which, as it turns out, is 314 divided by two).
7. There is an exact best time to celebrate Pi Day Because if you’re celebrating 3/14 for the sake of pi, you might as well go all out and time it to its most common approximation, 3.14159 … meaning, break out the party hats and pie on 3/14 at 1:59.
Happy Pi Day!
Editor's note: This article has been updated since it was originally published in March 2014.