Sunday, June 06, 2010

GED Math & Subtracting Negative Integers

Perhaps one of the most difficult concepts for learners to comprehend is negative integers. If you show them a problem such as 7-4, they know that the answer is 3.

But if you give them 7-(-4), they may still think the answer is 3.

So what is the best way to teach subtraction of integers, both positive and negative?

I have found that if you teach the basic method of "adding the opposite", that will help.

Example: 7-(-4)= ??

7 + (4) = 11

Step one: Keep the first integer 7
Step two: Change the negative sign to a positive sign
Step three: Change the sign of the second integer. In this case, The opposite of negative four is positive four.
Step four: Add the two integers.