Today is March 14, or "3/14," the first three digits of Pi. It's a day celebrated around the (geek) world as "Pi Day." Pi, of course, is the ratio of the circumference to the diameter of a circle. It was first recorded by Archimedes, but you can replicate his discovery in all kinds of ways.

Here's the pie version of Pi, the down, dirty and baked goods approach, illustrated by Brady Haran, a video journalist who loves numbers. He's in an ordinary parking lot. He unpacks an enormous number of identical, small pies — I can't tell what kind of pies, they look like a dense jam, maybe apple? Prune? But these aren't for eating, they're for counting ... and the math works out ... almost perfectly.