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What's the trick to Mental Math?

Anonymous Wed 20 Oct 06:25:19 2021 No.13770945 View Reply Original Report

Quoted By: >>13770955 >>13771154

Feels like anyone can do addition and subtraction of double digits in their head because of currency, but I'm talking fast multiplication of double or maybe even triple digits where each one is a sig fig eg 912*902
I want to appear smarter than I am.
are you supposed to represent with power of 10 technique?:
912= 9.12*10^2 and 902 = 9.02*10^2
3 sig figs on each side.

Anonymous

Anonymous Wed 20 Oct 2021 06:29:15 No.13770955 Report

Quoted By: >>13770976

>>13770945
Just do what you do on long multiplication but do it in your head. You should be able to keep track of 4 numbers and add them up

Anonymous

Anonymous Wed 20 Oct 2021 06:37:44 No.13770976 Report

Quoted By: >>13771106

>>13770955
>You should be able to keep track of 4 numbers and add them up
checked but I'm always drunk and high so I can't even multiply more than one number at a time. I'm retard-tier at this point.

Anonymous

Anonymous Wed 20 Oct 2021 08:02:41 No.13771106 Report

Quoted By: >>13771150

>>13770976
>what’s the trick to mental math
>I’m always drunk or high

Get yourself sorted out first Anon

Anonymous

Anonymous Wed 20 Oct 2021 08:23:20 No.13771150 Report

Quoted By:

>>13771106
don't you see that the calculator in my pocket does all my thinking, and soon it will do all of your thinking?

Anonymous

Anonymous Wed 20 Oct 2021 08:25:55 No.13771154 Report

Quoted By: >>13771188

>>13770945
900 + 2
/thread

Anonymous

Anonymous Wed 20 Oct 2021 08:38:41 No.13771188 Report

Quoted By:

>>13771154
That's what I thought, but then I can't quite understand the algorithm. Let me try again, but in the way I would try when I was young and off the drugs. Before coding and kush ruined my brain.
this is the way I'd do it in my brain...
912*902
=912x900+912x2
=91200x9+1824
=(91200*10-912)+1824
=(
at this point I would completely forget everything and give up and use a calculator
My brain likes rounding things to the nearest 5 or 10 like I'm working with change almost. I feel like I'm doing mental math wrong if it's not money. 912*902 is actualy easy cuz there's some property with 900^2 being 810000 and then there's something else but I forgot what. I got pretty good with math despite being drunk and high as fuck in college.

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