Mental abacus

{{Short description|Method of mental calculation}}

The abacus system of mental calculation is a system where users mentally visualize an abacus to carry out arithmetical calculations.{{cite web|url=http://www.shuzan.jp/english/brain/brain.html|title=Research on the benefits of mental abacus for development|accessdate=March 12, 2012}} No physical abacus is used; only the answers are written down. Calculations can be made at great speed in this way. 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.{{citation |url=https://www.theguardian.com/science/alexs-adventures-in-numberland/2012/oct/29/mathematics |title=World's fastest number game wows spectators and scientists |journal=The Guardian |author =Alex Bellos |author-link =Alex Bellos |year=2012}}

This system is being propagated in China,{{cite web|url=http://www.sh.xinhuanet.com/2004-04/13/content_1964401.htm|title=(Chinese)Teaching Kids Visit to use abacus for mental calculation|accessdate=March 12, 2012|archive-url=https://web.archive.org/web/20170213082310/http://www.sh.xinhuanet.com/2004-04/13/content_1964401.htm|archive-date=February 13, 2017|url-status=dead}} Singapore, South Korea, Thailand, Malaysia, and Japan. Mental calculation is said to improve mental capability, increases speed of response, memory power, and concentration power.

Many veteran and prolific abacus users in China, Japan, South Korea, and others who use the abacus daily, naturally tend to not use the abacus any more, but perform calculations by visualizing the abacus. 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{{cite book | last=Feynman | first=Richard | title=Surely you're joking, Mr. Feynman!|chapter=Lucky Numbers | publisher=W.W. Norton | publication-place=New York | year=1985 | isbn=0-393-31604-1 | oclc=10925248}} roots.