# Help choosing a system for mental math

**URL:** <https://forum.artofmemory.com/t/help-choosing-a-system-for-mental-math/32751>\
**Category:** Mental Calculation, Mathematics, and Puzzles\
**Created:** [August 4, 2017, 10:45pm UTC](https://forum.artofmemory.com/t/help-choosing-a-system-for-mental-math/32751 "2017-08-04T22:45:48Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![RubiksKid](https://forum.artofmemory.com/user_avatar/forum.artofmemory.com/rubikskid/32/2559_2.png) [@RubiksKid](https://forum.artofmemory.com/u/RubiksKid)\
**Post date:** [August 16, 2017, 9:34pm UTC](https://forum.artofmemory.com/t/help-choosing-a-system-for-mental-math/32751/6 "2017-08-16T21:34:25Z")

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> [@](#):
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> I like to be able to calculate when there is no way of writing things down. Like while driving a car for example.

Exactly. And as a future engineer, I find it to be a very attractive facility to have. The techniques even lend themselves to integration. After plugging in the limits of integration, mental math could make the evaluation process very quick (I imagine).

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> As the numbers get bigger, the chances of shortcuts become smaller. In the end only the criss cross method is able to do the biggest of multiplications.

That was my suspicion.

You said that you would recommend that I memorize squares. How far up should I memorize them? I read somewhere that 30 is a good point. Would you agree?

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> Learn to quickly calculate them when not memorized.

That makes sense. Calculate squares using shortcut methods, then step up or down until you reach the target number.

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> It does and af far as I know there is only one system to calculate those large numbers.  
> I am working on a separate post about this method.

Awesome! I’ll keep an eye out for it.

> [@](#):
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> Keep in mind that those people who can do that extremely quickly have worked with the soroban their whole life.

I’ll probably give it a try. I can already add/subtract quickly, but it’d be really cool to learn to add/subtract 4 or 5 digit numbers in a couple seconds. Hopefully that will be achievable. I’ll probably start with around 20 minutes/day, and then I’ll see where I am in 3 years or so. I guess it could only help.

Thanks again for all your time, Kinma. I really appreciate it. 🙂

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