Pi Day: What is it and why do we celebrate?

It's the occasion to celebrate the mathematical enigma of Pi.

It's World Pi Day today, an occasion to celebrate the "irrational and transcendental number", have conversations about math or just indulge yourself with some actual pie. Pi has a day dedicated to it because it is one of the most recognised constants in mathematics. It represents the ratio of a circle’s circumference to its diameter.

Pi is endlessly mysterious , a decimal that has no end. Most commonly, it is approximated with the fraction 22/7. It has been calculated to more than 50 trillion digits beyond its decimal point.

“Probably no symbol in mathematics has evoked as much mystery, romanticism, misconception and human interest as the number pi," author and math professor William Leonard Schaaf once said.

Pi Day is celebrated globally on March 14th (3/14) , in a nod to the first three digits of its approximate value (3.14159).

There are many ways in which you can usher in the day. Baking pies, organising Pi scavenger hunts and making  Pi-related artworks are some of the activities suggested by the Pi Day website.

You can also buy some Pi Day merchandise, which includes trendy printed t-shirts.

Some trivia about Pi

- The world's two most famous physicists have connections to Pi Day. Albert Einstein was born on March 14 (1879). Stephen Hawking died on March 15 (in 2018).

- There is a perfume named ‘Pi’, which claims to enhance male attractiveness. It is marketed by designer label Givenchy.

- Before the 1700s, Pi had no name and was called “the quantity which when the diameter is multiplied by it, yields the circumference". To do away with the clunky sentence, mathematician William Jones started using the symbol for pi (π) in 1706.

- Pi Day was first celebrated on March 14 by Physicist Larry Shaw. He later became popular as the Prince of Pi.

- Competitions to calculate more digits of pi continue to this date. In 2010, an American computer wizard and a Japanese engineer set the record of calculating up to 5 trillion digits of pi.