
Trachtenberg System for Rapid Mental Calculation - jpamata
https://en.wikipedia.org/wiki/Trachtenberg_system
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sharemywin
I always thought this was a neat trick:

[http://www.archimedes-
lab.org/Maths2_Multiplication.html](http://www.archimedes-
lab.org/Maths2_Multiplication.html)

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alfredallan1
This seems, at a high level, similar to the various mental arithmetic
tricks/pnemonics from India, commonly known as “Vedic Mathematics”. e.g.
[https://www.quora.com/What-are-some-of-the-best-Vedic-
math-t...](https://www.quora.com/What-are-some-of-the-best-Vedic-math-tricks)

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gshubert17
I came across this book in the 1960s and remember working through the
different algorithms. The only one I remember now is multiplication by 11.
More generally, I was not reluctant to do mental arithmetic in school,
especially for approximations and sanity checks.

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yoz-y
The multiplication by 3 seems quite more complicated than just multiplying
digits by 3 and carrying over the rest.

