Q&A #9415

Teachers' Lounge Discussion: Integers

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From: Teresa Fusco

To: Teacher2Teacher Public Discussion
Date: 2002111911:34:47
Subject: subtracting a negative (4 - - 2 = 6)

A new way I learned to "see" how subtracting a negative is adding a
positive is:

4 - - 2 = 6

Draw +1 in a circle for each of the first number (or whatever sign
applies to another set of numbers in your problem), so in my example
you have four small circles with +1 inside.

Now, you can not take away any negatives because you only have
positives. However, +1 and -1 added together equal zero, so 

add two sets (I am going to need 2 negatives in MY problem, yo need to
see how many are needed in different problems) of +1 -1 to your set of
four +1's from above.

Now, you have four +1's and two +1's and two -1's.

If you cicle and pull out two -1's (which is subtracting 2)
you are left with the four +1's and the two +1's which equals +6 which
is the answer!

get it?

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