This video will explain it all (warning: large! 23M).

Well, not all, but a lot. And, if you can’t quite make out what the sock puppets are singing about, try this page.

Perfect circles three-sided squares and two nested pairs with just one number. Isaac Newton’s fourth law of motion, rivers and oceans on the moon. Easter Sunday in the fall and Pope John Paul the Sixth or Seventh. Also the last digit of pi or large dragonflies that eat baboons.