Math geeks rejoice! Pi Day 2012 has arrived.

Founded on March 14 (3/14) by physicist Larry Shaw more than two decades ago, Pi Day has become known all over the world – both online and offline – as a time to rejoice and celebrate that wonderful mathematical marvel, pi.

For those not in the know, Pi is represented by the Greek letter π, and it is the most important numerical constant in mathematics. You can compute the area of a circle of radius r, using πr2. The perimeter of this circle has length 2πr.

Pi has been used for thousands of years in all sorts of calculations for physics, engineering and electrical systems. Without pi there is no theory of motion and no understanding of geometry. For instance, the volume of a sphere of radius r is 4/3πr3 and that of a cylinder of height h is πr2h.

While the number – normally rounded to 3.14 – has been used for thousands of years in all sorts of calculations, it also has cultural significance, showing up on T-shirts, mugs, Christmas ornaments, cookie cutters and posters. There are pi websites and pi Facebook pages. And, in the ultimate sign of devotion, some fans tattoo the pi symbol on their bodies.

“I think people think there’s something deep and philosophical about these mathematical constants,” said John Hasenbein, an associate professor with the Cockrell School of Engineering at the University of Texas.

So, what does one do to celebrate Pi Day 2012?

Suggestions from the National Council of Teachers of Mathematics include planning a pi recitation contest followed by a PIe eating contest (PcWorld has a pi shaped apple pie recipe here) and making your pies square, instead of round, since “pie aRe squared” is the surface area bounded by a circle.

If that does not excite you, you could always follow the schedule of Pi Day activities designed by self-proclaimed tech geek Harry Mylonadis.

His suggested activities include cooking π(Pi)ancakes, making crop circles and calculating pi by throwing frozen hot dogs.

You could also sing some Pi Day songs such as “Happy Pi Day to You,” “Oh Number Pi,” and “Pi Day Song.”

How will you celebrate Pi Day 2012? Let us know in the comment section below.

via Patch