Did you know that March 14th is called Pi day? That’s because the first three digits of pi are 3.14 and every year, people collectively get together to celebrate the holiday, sometimes with a pie.

Pi is most prominently known as the answer to the ratio of a circle’s circumference to its diameter. So if the ratio does not come out to the first few digits of pi (3.14), then you might have to check your math again.

Since its creation in 1988, Pi day has been turned into an international holiday celebrated around the world. Pi is the irrational number taking the shape of the sixth letter in the Greek Alphabet, paralleling the letter P of the English language. Pi is the answer for the ratio of a circumference and a diameter of a circle, always continuous and never repetitive.

The start of Pi dates back to over 4000 years ago back to the days of the Babylonians with the knowledge having been passed through the hands of the Egyptians, the first to calculate the values, the Chinese, and of course, the Greeks. The first known usage of the Greek letter as the number happened in 1706 by William Jones but was not popularized until 1737 by Leonard Euler. Now with the help of technology, an application created by Google, the two-quadrillionth digit of pi is discovered by Emma Haruka Iwao. Though Pi is closely associated with the circle and the mathematics associated with the shape, it also appears in numerous formulas.