Briefly, Chisanbop works like an abacus. The fingers on your right hand keep track of the ones, and your left hand keeps track of the tens. Fingers are worth 1 (or 1 group of ten ) and thumbs are worth five (or five groups of ten).

Spread your fingers out above a flat surface. Keep your fingers straight, don't let them curl (it slows you down too much). Fingers that are touching the surface are "activated" and keep track of the numbers. To count to ten, start with your right index finger (one), then the middle finger (two), ring finger (three), pinky (four). To get to five, you simultaneously touch down your thumb and lift all four fingers. That is five. Six is thumb and index finger, seven is thumb and index and middle finger, etc., up to nine.

After nine, you simultaneously touch down your *left* index finger, and lift the fingers on your right hand (ten). The progression for the tens on your left hand is the same as the ones on your right. Index finger is 10, index and middle is 20, index + middle + ring = 30, index + middle + ring + pinky = 40, thumb = 50, thumb + index = 60, etc. The result is a unique representation for all the numbers from 1 to 99.

_The Complete Book of Fingermath_ starts you off with this, then gives you shortcuts, and math problems, and tells you how to use it for somewhat more advanced problems.

--Pat Willette