The abacus system of mental calculation is a system where users mentally visualize an abacus to carry out arithmetical calculations.
For example, in the Flash Anzan event at the All Japan Soroban Championship, champion Takeo Sasano was able to add fifteen three-digit numbers in just 1.7 seconds.
[2] This system is being propagated in China,[3] Singapore, South Korea, Thailand, Malaysia, and Japan.
This was verified when the right brain of visualisers showed heightened EEG activity when calculating, compared with others using an actual abacus to perform calculations.
The abacus can be used routinely to perform addition, subtraction, multiplication, and division; it can also be used to extract square and cube[4] roots.