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Q&A #4824


A different way to subtract than normally taught

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From: Jeanne (for Teacher2Teacher Service)
Date: Oct 06, 2000 at 19:38:31
Subject: Re: A different way to subtract than normally taught

Hello Val,

I have not heard of "nick's method," but there are different ways of
regrouping than the way you described (which is the way I was taught also).

The method we were taught is like the following:
     34  --->   20 + 14    This is where we "borrowed from the tens place."
    -18  --->  -10  - 8    Subtract 8 from 14 to get the ones place.  When
    ---        --------    we did 2-1 we were actually doing 20-10 to get
                10 +  6 --->  16       tens place.

Here are two possible ways your daughter's class could be looking at
subtraction:

One method:
     34  --->   20 + 14    Break the 34 down into 20+14 since 18 is
    -18  --->  -18         easy to subtract from 20.  Remember the 14 to add
    ---        --------                        later.
                 2 + 14  ---->  16

Another method:
     34  --->   34       Break down the 18 into 14 + 4 and subtract first the
    -18  --->  -14 - 4   14 and then the 4.
    ---        ---------
                20 - 4  ---->16

And there are other ways. I can remember subtracting from left to right
before I was taught to subtract from right to left.
     34   --->   24    From here I did a compensation method similar to
    -18         - 8    the first method I shared with you to get the an
    ---         ---    answer of 16.

Hope this helps.

 -Jeanne, for the Teacher2Teacher service

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