# Adding Integers - Algebra

**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.