AC, that is completely stupid math manipulation. This is why kids have trouble with math, taking a one step problem and making it a 3 step.
First, make 20 into two values, 10 and 10. Then, subtract 9 from one of the 10s leaving 1. Now, add 1 to the other 10 and you get 11. Completely assine and schools should be embarrassed for this type of BS.
It’s showing why if you were to do the problem the old fashion way you would scratch off the two and draw a little one to borrow(or regroup).
Basically you are putting a 1 in the 10s place to represent 10, and a 10 in the ones place so you can do 10-9. After subtracting you are left with 1 in the ones place and 10 from the original.
In order to subtract 9 from 20, you first must understand how the 20 got there. Ah, two 10s. 10 take away 9 is 1. 1 plus 10 is 11. And that's how you get to the answer.
In order to subtract 9 from 20, you first must understand how the 20 got there. Ah, two 10s. 10 take away 9 is 1. 1 plus 10 is 11. And that's how you get to the answer.
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