## Happy Pi Day!

3/14/2011

Pi is the Greek letter we use to represent the number most often approximated as 3.14 (which is why March 14 is Pi Day).  Pi is one of those pesky irrational numbers.  It's an important one because it's the number that describes the relationship between a circle's diameter (the distance across the circle) and its circumference (the distance around the circle). Specifically, pi = circumference/diameter.

For a long time, we thought a circle's circumference was simply 3 times its diameter, but as we started to be able to draw more accurately, we started to notice that 3 wasn't quite right...

Mathematicians tried to figure out what the number actually was. Archimedes famously approximated pi by drawing regular 96-gons (polygons with 96 sides) inside and outside of a circle to get as close as possible to the actual measure of the circumference of the circle.  He figured out that pi is between 223/71 and 22/7.

Since pi is irrational, it can't be written as a fraction, and its decimal form goes on forever without repeating.  We're still finding digits to pi--and we always will be!

Here's a musical interpretation of pi to celebrate pi day: http://www.youtube.com/watch?v=iOjsRyxL7Rs.  Amazingly, it sounds pretty good!