Dr. Cotter on Subtraction Approaches

There are at least eight different ways to subtract multi-digit numbers. Even though a person has learned one method, it is good to explore other methods to enhance understanding.

If a child has an accurate and efficient method of subtraction, do not insist that the child change to a new method, rather encourage them to try a different method and see if they like it.

Subtraction can proceed from left to right like division. This is taught in RightStart Mathematics Level C.

subtract from left

Here subtraction proceeds from right to left, as in the traditional method used in the U.S. and Canada.

9062-5146

subtract from right

Also, subtracting on side 2 of the AL Abacus makes it virtually impossible to subtract 2 from 6 as some children want to do in the following example:

62-46

 

 

 

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