The first official Pi Day celebration was on March 14, 1988 and, of course, included feasting on some tasty pies. Educators caught on and appreciated the idea of teaching pi while eating pie. The movement prompted the U.S. Congress to officially declare March 14 National Pi Day.

Pi exists because circles exist. Draw any circle and measure its circumference (the distance around it), then divide that value with the length of its diameter (the distance across it). Whether you’re measuring the size of our solar system or something microscopic like an atom, the ratio of a circle’s circumference to its diameter is always pi—it is a universal constant. Although pi is an irrational number and not infinite, pi has an infinite number of decimal places. People have made it a challenge to memorize as many digits as they can, but, for practical applications, not many digits are needed. For calculation purposes, we use an approximate value of pi: 3.14.

Pi has countless applications beyond the classroom and into the natural world. For example, it can help scientists understand phenomena that involve circular shapes, such as the orbit of the planets or the ripples created by a duck landing on the river.

Albert Einstein was born on Pi Day. Stephen Hawkings died on Pi Day at the age of 76.

Although Pi Day is celebrated on March 14 (3/14), the exact time for celebration is 1:59 p.m. so that the exact number 3.14159 can be reached.

What do you get if you divide the circumference of a jack-o’-lantern by its diameter?

Pumpkin pi.

There are many records that show that pi was discovered a long time ago. The Babylonians knew of pi approximately 4,000 years ago. Evidence shows that Babylonians calculated pi as 3.125.

The King James Bible also gives an approx value of pi as the length of the forearm from the elbow to the middle finger tip.

What do you get when a bunch of sheep stand in a circle?

Shepherd’s pi.

What do you call a snake that’s exactly 3.14 meters long?

A python

The name pi and its symbol have been in use for over 250 years. They were introduced by William Jones, an Anglo-Welsh philologist in 1706 and made popular by the mathematician Leonhard Euler. There is an interesting reason why the name “pi” was coined. Before that, mathematicians had to say a mouthful; the only descriptive phrase they could use was “the quantity which when the diameter is multiplied by it, yields the circumference.”

What do you get when you take a bovine and divide its circumference by its diameter?

A cow pi.

The roundest knight at King Arthur’s table was Sir Cumference.

He ate too much pi.

The record for reciting the most number of decimal places of pi was achieved by Rajveer Meena at VIT University, Vellore, India on 21 March 2015. He was able to recite 70,000 decimal places. To maintain the sanctity of the record, Rajveer wore a blindfold throughout the duration of his recall, which took an astonishing 10 hours!

Can’t believe it? Well, here is the evidence:

http://bit.ly/piproofTRR