Pi Day is celebrated across the world on March 14. Pi Day celebrates the mathematical constant π (3.14). It is celebrated in countries that follow the month/day (m/dd) date format, because the digits in the date, March 14 or 3/14, are the first three digits of π (3.14). Pi Day was founded by Physicist Larry Shaw in 1988. We all can celebrate the special day with something special to be done Mathematically or just eat pies !!