It sounds like a toddler’s attempt to say “Friday” or, even better, a day to gorge on apple crumb or coconut cream. Alas, “Pi Day” is something completely different. It’s a commemoration of a mathematical constant that’s represented by the Greek letter pi – one of the most important quantities in science.

Pi is the ratio of a circle’s diameter to its circumference. When it’s rounded off to two digits, it’s 3.14 – the numerical equivalent of March 14th.

Astronomers use pi to calculate the volume and density of a star or planet, the details of an orbit, and much more. Other scientists use it as well.

But pi is an “irrational” number. That means that no matter how long you calculate its exact value, you never reach the end – whether you go to a thousand decimal places, a million, or rbrm eleventy-jillion. There’s never a conclusion, and no group of numbers ever repeats. Mathematicians have used various techniques to try to calculate the exact value, without success. The record so far is more than a hundred trillion places to the right of the decimal.

Trying to calculate an exact value has been an important plot point in science fiction. Any time a computer is getting too uppity, it’s commanded to calculate pi to the last digit. That impossible task overloads the computer, allowing the heroes to regain control. Whether we’ll need it to rein in A-I – well, have a slice of pie – the tasty variety – while you ponder it.

Script by Damond Benningfield