Every March 14 (3.14) is Pi Day. Pi is the ratio between a circle’s circumference and its diameter. Since this ratio is approximately 3.14 for a circle of virtually any size, pi is known as a mathematical constant.

Pi is also a fascinating number because its decimal representation never ends and never settles into a permanent repeating pattern. Countless math heads and not a few super computers have divided this ratio out past a million decimal points and have not found any kind of repeating pattern for this ratio!

And this year Pi Day is especially significant because it is the year 2015 and the two decimals that follow 14 in the ratio are 15 so it matches the day of the month, the month and the year: 3.14.15.

So here are some ideas for celebrating Pi Day.

1. Eat a piece of pie.

2. Try to draw a perfect circle.

3. Watch the movie Life of Pi (The is one of my all-time favorite movies and I promise you it is not a boring movie about numbers. The book is great too.)

4. Ponder other mathematical wonders like the Fibonacci Sequence and the Golden Ratio.

5. Take your favorite mathematician out to lunch.

I’d like to hear some other ideas for celebrating Pi Day.

Pi is represented by mathematicians by the Greek letter of the same name shown here: