March 14 is Pi Day, an annual celebration of the mathematical constant of pi, representing the ratio of a circle's circumference to its diameter. The holiday is observed on March 14 or 3/14 because 3.14 are the first three digits of the infinite number pi — 3.14159 ... and on and on.

It's National Pi Day, so treat yourself to some pie — pizza, dessert or both, whatever your heart desires! That first "Pi" isn't a typo and differs from the tasty "pie" we eat, though we could easily draw some geometric similarities between the two.

At an event outside Tokyo in 2006, Akira Haraguchi set an unofficial world record for reciting the most digits of pi: 100,000 over more than 16 hours. So, how’d he do it? In his mind, he linked each digit with a syllable and created a collection of epic stories from the words those syllables formed.