You don't necessarily have to be a small child or an idiot to do arithmetic on your fingers. Various methods of "finger math" have been used for millennia, exploiting concepts of place value similar to those involved in the operation of the abacus. In Korea, digital (in the original sense of "digit") arithmetic is known as Chisenbop.

In Chisenbop, the fingers are valued as follows:

  • Right thumb: 5
  • Right fingers: 1 each
  • Left thumb: 50
  • Left fingers: 10 each
As you can see, any positive integer up to 99 can be represented on a 10-fingered human hand with this method. Rules for elementary arithmetic operations are straightforward, although it'd probably take a bit of practice to become proficient. With a fair amount of manual dexterity and the inclusion of knuckles, finger-counting techniques can be extended from the basics of Chisenbop to larger numbers.

The Chisenbop technique was imported to the United States in the 1970's and 1980's. Infomercials featured Korean kids outperforming electronic calculators with flying fingers, and Chisenbop tapes and books became an educational fad, instituted in many elementary and middle school curricula.

Finger counting is best understood visually, and there's a good interactive tutorial on the subject at You might be able to find a Chisenbop book at your local library, but don't count on it.

Originally the subject of mockery by those forced to learn it as children, Chisenbop has become a sort of in-joke among the purveyors of popular culture. In episode #102 ("The Funeral") of The Tick, the loutish protagonist fumbles his fingers and shouts "Chisenbop!," only to get an utterly absurd solution to his problem. Finger math has also been employed by the rural Alaskans of Northern Exposure.