Play the USA TODAY Daily Crossword Puzzle. What does Pi Day mean Pi Day is an annual celebration of the mathematical constant π (pi), observed on March 14 (3/14).

It is a day to celebrate mathematics, Albert Einstein's birthday and, of course, eat pie. The numbers of the date 3/14 are the first three numbers of the mathematical number for pi 3.14.

This Thursday and Friday, March 13 and 14, area restaurants are honoring 313 Day and Pi Day with a few special deals. ... Play the USA TODAY Daily Crossword Puzzle.