# International Pi Day : 14 March

**International Pi Day : 14 March**

Pi Day is a celebration of the mathematical constant π. Pi Day is observed on 14 March.

The day was chosen as 3, 1, and 4, which are the first three significant digits of π.

Pi is one of the most well-known mathematical constants. It is the ratio of a circle's circumference to its diameter. It is represented by the lower-case Greek letter π.