Pi — the ratio of a circle’s circumference to its diameter — is one of the world’s most famous numbers. The ancient Babylonians, who were the subject of a recent blog here on Morris Tutoring, were the first to calculate a value for pi.

Pi is an infinite, non-repeating decimal that, so far, passes all tests of randomness. That means, for example, somewhere in its endless string of digits you will find your social security number and your birthday. If you doubt this, go to angio.net/pi and try it. For example, the digits 03142020 — the date of Pi Day this year — occur at position 18900827 and two additional times in the first 200 million digits of Pi. Whoa!

Pi is also transcendental, meaning that it is not the solution to any polynomial equation.

In 1988, March 14 — 3.14 — was established as Pi Day by physicist Larry Shaw of San Francisco’s Exploratorium, an interactive science museum. The U.S. House of Representatives officially recognized it 21 years later, when it passed HRES 224, in 2009.

Most people who know pi know it only as 3.14, or perhaps 22/7. Or simply as a key on their computer. Lu Chao of China knows pi to 67,890 digits — a Guinness World Record. An easy mnemonic to remember the first 8 digits of Pi is this: “May I have a large container of coffee.” The number of letters in each word represents a digit: 3.1415926. This is also an example of a writing style called Pilish, in which the number of letters in each word represents a successive digit of Pi. Here’s a poem (called a piem) written in Pilish:

Wow (3), a (1) star (4)

A (1) fiery (5) supernova (9)

In (2) cosmic (6) burst (5)

Wow! (3)

Here’s a longer example of Pilish, composed more than 100 years ago by the English physicist Sir James Jeans: “How I need a drink, alcoholic in nature, after the heavy lectures involving quantum mechanics!”

In 2019, Emma Haruka, a Google cloud developer, used a supercomputer to calculate pi to 31.4 trillion digits, breaking the previous record of 22.4 trillion digits set in 2016. In “The Wolf in the Fold,” an episode of the original *Star Trek* TV series, Mr. Spock was able to destroy an evil alien computer by challenging it to calculate the last digit of pi!

By the way, Pi Day is also the birthday of Albert Einstein (born March 14, 1879), in honor of whom Princeton University holds an Albert Einstein look-alike contest each year. Speaking of institutes of higher learning, the Massachusetts Institute of Technology (MIT) mails its annual acceptance letters to applicants each year on Pi Day.

In 2015, Pi Day was special. At 9:26:53 a.m. and p.m., then never again, the date and time contained the first 10 digits of Pi: 3.141592653.

There are many formulas — dozens, if not hundreds — that can be used to calculate pi. One of them is: Pi = 4(1 – 1/3 + 1/5 – 1/7 + 1/9 – 1/11 …). The others are nearly impossible to type using a word processor.

Mathematicians, scientists and teachers promote Pi Day as a way to increase interest in STEM topics. Schools, museums, clubs and groups across the country will help to celebrate by holding exhibitions, contests (how many digits of pi can you recite?), pie-eating and even pie-throwing contests. So be sure to duck.