March 14 apparently is Pi-day, since it read as 03-14 (as in, 3,14).

However, I read somewhere that we should actually be celebrating Tau day (which, I think is basically Pi times two), since that is the number you’d actually use to calculate a circle.

The day to go with that should then be, err, june 22nd.

If you’re into math and crazy arguments, go check out the Tau manifesto.