Soroban, japanese abacus (soroban, japanese abacus)
Soroban, the Japanese abacus, is made of a wooden frame with vertical bars on which beads can move freely. It was used by merchants and accountants for centuries. Today it has been replaced by electronic calculators but is still used by older generations and as a teaching tool. A trained soroban user is often quicker calculating than modern calculator users. By visualizing in your head the soroban, mental arithmetic can be achieved much quicker.
External links :
http://en.wikipedia.org/wiki/Soroban
http://www.betteratmath.com/how-to-use-a-soroban-sato-soroban-method/
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