March 14 is unofficial holiday known as National Pi Day because the numbers in the month and date correspond with the first three digits of π (3.14), according to timeanddate.com.

Pi is a name given to the ratio of the circumference of a circle to the diameter, meaning for any circle you can divide the circumference by the diameter and always get exactly the same number, which is approximately 3.14159, according to math.com.

By the way, March 14 is also Albert Einstein’s birthday. Wonder if he had a favorite type of pie—apple, cherry, pizza?

Tell Us: Who's got the best pie in Niles and Morton Grove?

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