Chisenbop

Chisenbop is a method of using the fingers much like an Abacus to perform basic math operations. It is said to be of ancient Korea origin.

= Basic concepts =

The hands are held in a relaxed posture on or above a table. All fingers are floating off the table to begin with. The fingers are pressed into the table to indicate value.

Each finger (but not the thumb) of the right hand has a value of one. Press the index finger of the right hand onto the table to indicate one. Press the index and long fingers for two, the three leftmost fingers for three, and all four fingers of the right hand to indicate four.

The thumb of the right hand holds the value five, like the top bead of a soroban or abacus. To place the value 6, press the right thumb and index finger onto the table. The thumb indicates 5 plus the 1 indicated by the finger.

The left hand represents the tens digit. It works like the right hand, but each value is multiplied by ten. Each finger on the left hand represents ten, and the left thumb represents fifty. In this way, all values between 0 and 99 can be indicated on two hands.

= Chisenbop notation =

A notation system for representing the numbers would be handy. I propose the following convention:

. = a finger off the table o = a finger on the table - = a thumb off the table @ = a thumb on the table

Values between zero and 9 are shown with the entire right hand:

-.... = 0 -o... = 1 -oo.. = 2 -ooo. = 3 -oooo = 4 @.... = 5 @o... = 6 @oo.. = 7 @ooo. = 8 @oooo = 9

Values larger than 9 are shown with both hands:

..oo- -.... = 20 ....@ @.... = 55 .ooo- @o... = 36

= External links =

*[http://www.cs.iupui.edu/~aharris/chis/chis.html Interactive demonstration of Chisenbop]