Today is Pi Day, for obvious reasons. Pi is a Greek letter representing the ratio of a circle's circumference to its diameter, a mathematical constant. If a circle's diameter is one, its circumference is approximately Happy Pi day.

Triple Berry Pi Day Pie - An easy berry pie gets a mathematical update for Pi Day, of course.

Great High School Math Poster on Pi . Okay, it's not funny, but it's 'Pi'.

18 delicious pies you need to try. There are dessert pies, dinner pies and even a breakfast pie. Engraved Pi Plate giveaway from GoneGirly on Etsy.