It's a great day for fans of math (or pies, pizza or otherwise). It's Pi Day!

(Yes, there are people like us out there).

Pi Day, held every year on March 14, is a celebration of the infinitely non-repeating mathematical constant that helps us calculate the ratio of a circle's circumference to its diameter. The number is usually rounded up to 3.14 (or, 3.14159 if you want to show off), but it can go on forever. In fact, a Google employee named Emma Haruka Iwao recently set a new record by computing Pi to 31.4 **TRILLION **decimal places. The online search giant announced Iwao's record-setting Pi calculation on Pi day which was calculated using 25 Google Cloud virtual machines to do the math.

Pi was first used by the ancient Babylonians that calculated the area of a circle by using three times the square of its radius. The Pi symbol math teachers made you learn, was first used in 1706 by mathematician William Jones and later popularized by mathematician Leonhard Euler.

Another Pi Day fact you might find useful for your next bar trivia night: Famed physicist Albert Einstein was born on 3/14, and is also the date of Stephen Hawking's death.

Today isn't all about nerdy math. In fact, today's unofficial celebration of everyone's favorite irrational number is a great excuse for companies to offer specials and deals.

- Bakers Square: $2 off any pie. You can also get the pi symbol baked on double crust and fruit pies.
- 7/11: Using the 7Rewards App, customers can get one slice of pizza for 50 cents, or a whole pie and get 314 7Rewards points.
- Boston Market: Customers can get a free rotisserie chicken pot pie with the purchase of another pot pie and drink with a coupon.
- BJ's Restaurant and Brewhouse: A mini one-topping pizza can be yours for $3.14.
- California Pizza Kitchen: A slice of Key Lime pie can be yours for $3.14.
- Blaze Pizza: Use the app to get a $3.14 pizza all day today (One per customer).
- Whole Foods: Customers can get a $3.14 discount on a large bakery pie's regular price.

*Photo: Getty Images*