use the chisanbop

Chisanbop is a korean method of using your ten fingers as an abacus and calculate with numbers from 1 to 99. )beginner(
Every fingers of the right hand )index, middle, ring and pinky( stand one, the thumb for 5.
Its the same on the left hand but with 10 except for the thumb which counts for 50.
If you want to learn the chisanbop )or chisenbop( you can try this websites:
http://en.wikipedia.org/wiki/Chisenbop
Here is a tutorial:
http://www.cs.iupui.edu/~aharris/chis/chis.html