2014-06-22 11.14.14When I first saw this in Reddit I thought it was pretty cool, why it was posted as a Japanese Visual multiplication method I don’t know since there was nothing in the comments saying it was Japanese.  But anyway, the idea is pretty simple.  To multiply two numbers between 11 and 99 you simply draw the corresponding number of lines as a crossing pattern.  I did my own and posted the picture, so lets walk thought it.

In this case we are going to multiply 24 x 52.

Starting with the number 24, lets draw 2 lines representing the ten’s digit of 24.  So you can see I drew two lines from right to left at the top.  Next I drew 5 lines below the two I drew above.  The 4 lines represent 1’s digit of 24.

Next I do the same thing but in the other direction for 52.

Now lets count the number of intersections.  Starting from the left, I counted 10 intersections.  So I wrote down 10.   Next I count the total of intersection in the center. That is 4 at the top, and 20 at the bottom.  I could have saved time here and simply wrote down 24, but I wanted to show my work, so I left the 20 and the 4 to be added at the end.  Finally I counted the total number of intersections on the right and found 8, thus writing down 8.

Finally, we total these things up.

10

20

4

8

1 2 4 8  = 1248

Pretty cool eh?  Then to check my work, I did the same thing the way we were all taught in school and totaled it in 10.  I do not know how much time it took me to do this hatching exercise but WAY more then 10 sec.  So for actual use, this is not practical at all, but perhaps as a way to teach what is going on to children when multiplying, perhaps.

Following a link I found a video by Vi Hart explaining this.  As we can see from her video, once you start doing large number, say 88×99, this techniques becomes messy and impractical.  However this got me doing so other searches and seems there are quite a few visualization techniques for multiplying, so check around.

 

 

 

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