From pizza pies to dessert pies, many businesses and restaurants are offering deals to celebrate Pi Day. Want a slice of the celebration? Here are 10 "irrationally" good deals in the Chicago area.

First Slice Pie Café in Chicago is offering a Pi Day deal at their Montrose, Manor and Andersonville locations. They’re offering slices of pie for $3.14, mini pies for $6.28 and whole pies for 20% off. Those who are in the store at 3:14 p.m. will also receive an "exclusive surprise," according to the shop's Instagram post.

Pi Day, celebrated on March 14 each year, honors the mathematical constant π with plenty of deals on sweet and savory pies, making it a perfect day for math lovers and food enthusiasts.