Quick! Get out your favorite circular objects to celebrate Pi Day!

As the math and science enthusiasts among us already know, March 14 (i.e. 3/14) is officially Pi Day — a day to celebrate the number Pi, identified by the Greek letter π, which is used to calculate the circumference of a circle.

Due to its length, Pi is typically shortened to 3.14. But because the number is both irrational and transcendental, it “will continue indefinitely without repeating,” as the official Pi Day website kindly explains.

With the use of handy computers, Pi now calculates out to more than one trillion digits beyond the decimal. The very mysterious nature of Pi — the fact that it can never be entirely known — helped generate the adoration for the nyumber held by the mathematically inclined.

Welsh mathematician William Jones first used the famous Greek letter as a symbol for for Pi in his work *Synopsis Palmariorum Matheseos* published in 1706. But the symbol didn’t really gain widespread popularity until Swiss mathematician Leonhard Euler adopted the Greek letter over 30 years later in 1737.

So what exactly is the purpose of Pi Day?

“Mathematics and science can be a fun and interesting part of a child’s education, and learning about Pi can be an engaging way to teach children about geometry and attract them to study science and mathematics,” Congress stated when it officially designated Pi Day in 2009. “America needs to reinforce mathematics and science education for all students in order to better prepare our children for the future and in order to compete in a 21st Century economy.”

Pi Day was first celebrated in 1988 at the San Francisco Exploratorium, which remains one of Pi Day’s primary promoters. At the time, math enthusiasts paraded around the monument in a clockwise circle three and one-seventh times while singing “Happy Birthday” to Albert Einstein (March 14 is his birthday too). Today, Pi Day celebrations take place in countless grade schools across the country.

While a wide variety of Pi Day celebrations are acceptable, some of the more popular include circle-measuring parties, watching the movie *Pi *(1998), Pi recitation contests (to see who can accurately recall the most digits) and, of course, eating actual pie!

So get out there, and enjoy all things circular. The celebrating will make your math teachers proud!

*Updated March 13: Added details regarding Pi Day’s history.*

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