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no-espam
on March 6, 2012
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How to Divide any number By 9, 90, 900 and so on i...
Professor Trachtenberg (early 1900) comes to mind for doing speed math.
no-espam
on March 6, 2012
[–]
Wow, downvoted for posting info related to a professor who was held in nazi concentration camp and kept his mind lucid with math?
http://en.wikipedia.org/wiki/Trachtenberg_system
downx3
on March 6, 2012
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+1 for the Trachtenberg system. I only wish we were taught these methods at school, in addition to the 'normal' way...
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