3.3
Add and Subtract Negative Numbers
When adding and subtracting, we usually put parentheses around the negative numbers in order to clearly show that it is a negative number and not the operation subtraction.
Addition with Negative Numbers
4 + (3) = 4  3
What happens when the value if we add with a negative number? To add with 3 is the same thing as subtracting by 3.
4 + (3) = 4 – 3 = 1
When adding by a negative number the value will decrease. In other words, it is the same thing as subtracting by 3 in the example above.
Let’s take another example:
4 + (2) = 4  2
We start at the 4 and add by 3. This becomes the same thing as subtracting by 2.
4 + (2) = 4 2 = 6
Subtraction with a Negative Number
5  (2) = 5 + 2
What happens to the value if we subtract with a negative number? Subtracting by 2 is the same thing as adding by 2.
5  (2) = 5 + 2 = 7
When subtracting with a negative numbers, the value will increase.
Let’s take another example:
(4) – (3) = 4 + 3
We start at the 4 and subtract by 3. This becomes the same thing as adding by 3.
(4) – (3) = (4) + 3 = 1
