ADDING TWO \ALIKE SIGNS – two positive numbers or two negative numbers
First Method:
1. Add absolute values
2. Attach same sign to the answer
Example:
Adding two positives integers
4 + 5 = 9
Adding two negative integers
(-4) + (-5) =
(-9)
Second Method:
(+) positive (-) negative
Draw (+) and (-) to represent the number sentence.
Note: A pair of (+) and (-) cancels each other or equals zero. (See end of page for more an illustration.)
4 + 5 = 9
+ + + + and + + + + +
OR
(-4) + (-5) = (-9)
(-) (-) (-) (-) and
(-) (-) (-) (-) (-)
Parentheses are used for clarity only.
Are there any zero pairs to cancel? No. So, count the signs to get a total.
Memory tip for adding two integers with same signs:Alike Signs –Add
ADDING TWO UNLIKE SIGNS
- 6 + 4 = ?
First Method:
1. Subtract absolute values
2. Use the sign of the number with the larger absolute value
| - 6| = 6 | 4 | = 4
Remember to put the larger number first when subtracting two numbers. -- > 6 - 4 = 2
Six is larger. So, the answer will have a negative sign.
- 6 + 4 = - 2
Second Method:
Parentheses are used for clarity only.
(-) (-) (-) (-) (-) (-)
+ + + +
Are there any zero pairs to cancel? Yes. Four pairs cancel each other. So, count the remaining signs to get a total. Two negatives are left. Thus, - 6 + 4 = - 2
Memory tip for adding two integers with unlike signs:Different Signs – Find the Difference
Here is proof that a positive and negative cancel each other.
( -3) + 3 = ?
(-) (-) (-)
+
+ +
Three negative / positive pairs cancel each other. Thus, the answer is zero.