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Dora S
Math. - 20120319
It is said that someone calculate "123 x 321" by drawing lines, as the picture below. Is it true? Then will they draw nine lines for "9"？ Will they have to count many cross points?
2012年3月19日 14:04
修改 · 5
Math. - 20120319
It is said that someone can calculate "123 x 321" by drawing lines, as indicated by the picture below. Is it this true? Then will they Drawing nine lines for "9"？ Will they have to count many cross points? So many points to count.
Yes. You can multiply any two numbers using this method. They even have a video on youtube to show you how. Like you said, it is a very inefficient way to calculate because of all the preparation in drawing lines and counting the intersections.
2012年3月19日
@
@Michał， I think I can do it without fingers, :）
2012年3月19日
I can only multiply by 9 by fingers :). I've taught maths for few years as a tutor but I didn't hear about that. It's interesting.
2012年3月19日
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