Learning shortcuts and simplifiers

[Stryder50]

I'm guessing there may be a few of these to make a thread worthwhile.
I recall seeing this once before and forgot to post it somewhere. Just now saw it and here you go.
The video clip will explain this method. Looks shorter and easier than others, especially if you don't have a calculator (or slide rule like we had when I was in school);

The Japanese Way to Multiply Is So Much Cooler Than Ours​

You have to try it.

The Japanese Way to Multiply Is So Much Cooler Than Ours

You have to try it.

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