Multiplication without multiplication tables

-Captioned-
This way of multiplying two numbers dates thousands of years ago. It is sometimes called Egyptian or Ethiopian multiplication.
What is interesting is that it is not graphical, and doesn't use multiplication table.
After some practice, it can be quite fast.

AFTER SOME COMMENTS, I NEED TO ADD THIS:

This video is NOT going to show you a fast way to multiply.
The idea is just to show that there are alternate methods to the one everybody knows.
Don't tell me it's slow. I know it is.
It would be fast, we would still be using it, wouldn't we?
And I am not questionning the use of multiplication tables!

And don't bother to tell me it does or does not come from Middle East. I had enough comments about this. That is not the point of this video. Thanx.

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Category:

Education

Tags:

• math
• trick
• multiplication
• method
• technique
• without
• table
• tables
• calculus
• numbers
• multiply
• times
• egyptian
• ancient

[efrankl1]

this is Fun Math, do you think doing division is the exact opposite?

[TyYann]

@efrankl1 Actually, I found something like that. You multiply both column by 2 each time, and one column will start at 1. I might make a video on this in the future.

[ChocalateIpod]

wtf its easier doing it the original way. it takes hours doin it the way u show us

[TyYann]

@ChocalateIpod It's also quicker to read the video description...

[UTleochi]

Thank you for that nice video - I always love to discover new ways of playing with numbers and I think knowing more methods than those one has to learn at school is always refreshing. Sadly most people seem to be too lazy to use their brain to discover new paths. ;D

[TyYann]

@UTleochi You're welcome!

[maxmadx]

i guess im the idiot then. sorry

[RPalacios6]

u have hairy arms

[Gaiacarra]

I find it easiest to break it down into steps with distributivity

13 = 10 + 3

so 27 x 13 = 27 x 10 + 27 x 3

= 270 + 27 x 3

and 27 x 3 is easy

[zrylam]

as soon as i saw 27 x 13 i just did this in my head:

(average)^2 - (difference / 2)^2

= (20)^2 - (7)^2

= 400 - 49

= 351

much easier, just memorise your perfect squares lol

[ChocalateIpod]

@RPalacios6 ROFL hairy arms

[NehuAbhay]

Good to know a new technique ! Thanks.

[youlovemathematics]

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