I thought it was nice, even though if he started multiplying figures with numbers like 6 or 8 it would be pretty tedious

Math Lesson: A new way to multiply

Is there an explaination/proof of how this method works?

 

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Okay I was impressed at first but now I see that it's actually very simple.

It looks like a graphical way of doing the foil method. and then the counting is just doing the addition of the singles, tens, hundreds, etc. It is kind of neat looking, however, though as clarisse said multilying 79x989 would definately be slower than doing it via more traditional methods.

i'll use this when i have the time to do it for every question which i doubt i'll have, ever.