By Anupum Pant
Please note, in the heading I said, a fun way to multiply numbers, not necessarily a quick way. Widely touted as an “amazingly quick Japanese method to multiply”, I think firstly, it really is not a very quick method. Secondly, I couldn’t find any sources confirming that it is a method developed by the Japanese. In fact, I’m not even sure if there’s anything Japanese about it. Nevertheless, the method sure is fun and should work great for people who don’t remember the multiplication tables well.
Another great thing about it is that it is a multiplication problem turned into a visual counting problem. Since multiplication exercises don’t really make kids happy, they’d definitely love to count intersections instead (multiplication disguised intelligently).
Of course the counting can be used for single digit numbers too, but that won’t be too useful. For slightly more complex problems involving 2 digits like 32 X 42, it could be a life saver. It’s a fairly simple 3-step process. Here’s how you do 32 X 42 with it…
Step 1: The best way to go about it is by starting from the top left. First, you draw the 3 lines for the 3 of the number 32. And then you make 2 lines for the number 2, as shown.
Step 2: Next make 4 lines and 2 lines intersecting the previously made lines as shown. Clearly, 4 lines for the 4 of 42 and 2 lines for the units place of 42.
Step 3: Count the number of intersections in the far left (a), centre (b), and the far right (c). (a), (b) and (c) are 12, 14 and 4 respectively, for this problem.
The 1 from 14 gets carried to the number just at the right of it – 12 of (a), and (a) becomes 13. A similar carrying of the ten’s place to the immediate right column happens if there are any 2 digit numbers. So you are left with 13, 4 and 4 now. 1344 is the answer to 32 X 42.
This can be done for 3 digits too and more…
If there’s a zero, you could make a line and not count any intersections with it. As it has been shown in the video below…
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