March 14th is Pi Day, so enjoy some pie!

Today is March 14th, otherwise know as National Pi Day! It's an annual celebration of the mathematical constant, π.

In math, pi (π) represents the mathematical ratio of a circle's circumference to its diameter. Because it is an irrational number, it has an infinite number of decimals, but it's most often noted as 3.14 -- its first three digits. If you were curious, the National Pi Day official website has expanded it to a million places.

But many observe the day with a different sort of circle,  in the form of pie, or pizza. Several places that serve both even offer deals!

Here's a list of some places with Pi Day promotions. Keep in mind, offers can vary by location.