LionJim and other MATHS. 
geeks, what do you think of this?
Very clever, even though I don’t get it.
geeks, what do you think of this?Very clever, even though I don’t get it.
MATHS. [insert the face here] : Japanese multiplication method
- Thread starter BobPSU92
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Here's a better explanation of it and it's just a different way to write it outLionJim and other MATHS.
Very clever, even though I don’t get it.
Japanese Multiplication: The Real Reason Why It Works | Concreteness Fading
Have you ever seen someone share the Japanese multiplication method on social media? Often times, it looks like nothing more than a math trick. It's not!
tapintoteenminds.com
That’s really fascinating but was this method instituted because there’s a calculator shortage in Japan?
I can see that getting really difficult with higher digits with a lot of lines and counting (79 x 88)
Maybe. They used to make all the calculators there, but now they’re made in China or wherever.
Interesting, but I'm pretty confident I could do it the way we were taught in school faster than drawing all the lines and dots. (assuming calculators were unavailable)
Know your basic facts. Multiple and add seems to be simpler.
In the followup post by @4rosco, it talks about using arrays. Similar to cuisenaire rods.Usually used at lower grades up to maybe grade 4.
After that, IMO, use the multiply and add method.
When I taught “new” methods, I would teach them, teach mine and tell kids to use either or “mom/dad/grandma/grandpa’s” method. Whatever is easier as long as they learn it.
OL
In the followup post by @4rosco, it talks about using arrays. Similar to cuisenaire rods.Usually used at lower grades up to maybe grade 4.
After that, IMO, use the multiply and add method.
When I taught “new” methods, I would teach them, teach mine and tell kids to use either or “mom/dad/grandma/grandpa’s” method. Whatever is easier as long as they learn it.
OL
Did you notice that in none of the examples did the units terms multiply to two digits? (It’s an easy enough fix.)
Bottom line is that it’s just another way to show that 31•32=(30+1)•(30+2). I’m agnostic on it.
Bottom line is that it’s just another way to show that 31•32=(30+1)•(30+2). I’m agnostic on it.
Oh, sure. Make it more complicated. Are we multiplying or adding? You expect people to do both in one problem?
I like it because it reinforces that multiplication is just repeated addition. Obviously it is slow but anytime you can show younger people a visual approach and explain it well enough it is worth doing. Especially if your count is 10 or bigger.
Back in the 80s we had a guy in our Tokyo office that used an abacus. I bought one as a souvenir and tried it on the flight home. I gave up pretty quickly.
LionJim and other MATHS.
Very clever, even though I don’t get it.
I'd like to see them try this with decimals ... and large numbers ... like
9786.456 x 97.9894 =
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