Arithmetic Grade Five

Lesson Thirty-seven: Subtracting Negative Numbers


The difference between a negative and a positive number is the same as the sum of two negative numbers:


	-132 - 153 = 

	-132 + -153 =

The answer to both of these problems is -285. You probably noticed that 132 + 153 = 285. Our answer is -285. So, when you start with a negative number and you subtract a positive or add a negative, you ignore the signs and add the numbers and then put a negative sign in front of your answer.

Here's another example:


	-211 + - 44 = 

	-211 - 44 = 

In either case the answer is -255. You can see that 211 + 44 = 255 and by placing a negative sign in front of the 255 we get -255.

Of course, you should also realize that you can add a positive number to a negative number and wind up with a positive answer:


	-21 + 44 =  23

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