GRAND RAPIDS, (WZZM) -- Today is National Pi Day. Pi Day is celebrated on March 14th around the world because it is 3.14 and pi is 3.14159, which is the ratio of a circle's circumference to its diameter.
Pi is a constant number, meaning that for all circles of any size, pi will be the same.
In honor of Pi Day, the Grand Traverse Pie Company is giving away a free slice of pie Thursday with any purchase. The restaurant is teaming up with the Michigan Department of Agriculture to support state farmers this pie day.