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I learnt arithmetic in the early sixties. 99x5 would be 9x5x10+9x5 = 450+45 = 495 Perhaps it helped that we all knew the 12 times tables. Is there some new
by kwhitefoot 5y ago
I learnt arithmetic in the early sixties. 99x5 would be 9x5x10+9x5 = 450+45 = 495
Perhaps it helped that we all knew the 12 times tables.
Is there some new magical way of doing long multiplication that is more effective and easier to understand?
- coryrc 5y ago999999*5 is far easier as 5000000-5 than 45+450+4500+... Are you really arguing that the latter is faster and more effective to do in your head?
- kwhitefoot 5y agoNot at all. I didn't know we were discussing mental arithmetic.
- coryrc 5y agoEven on paper it's far simpler (1000000-1)*5 => 5000000-5 => 4999995 Learning to find these patterns early sets up students for having an easier time with algebra later. Algebra is just rearranging equations. I don't understand, but students do struggle with going from "12/3=?" to "3*X=12 solve for X". We can't keep failing so many students every year and expect our country to hold together.