Yes, the ratio of the circumference of a circle to its diameter has is own day also. It’s Pi Day. March 14th. Created by physicist Larry Shaw, Pi Day is a holiday commemorating the mathematical constant π (pi). There is a reason for this date. Pi Day is celebrated on March 14 (or 3/14 in month/day date format), since 3, 1 and 4 are the three most significant digits of π in the decimal form. If you want to check it out, here are the first one million digits of π. Ironically, this is also the date when Albert Einstein was born. So, how about some good music along with that, to celebrate it?!