Adding Integers and Developing Rules

- -9 -6
- Correct answer is -15
- What are you doing with the numbers?
- If both signs are negative how does that affect

your answer?

- -12 7
- Correct answer is -5
- What are you doing with the numbers?
- If the signs are different, how does that affect

your answer?

- 10 -6
- Correct answer is 4
- What are you doing with the numbers?
- If the signs are different, how does that affect

your answer?

Develop Rules

- If you are adding integers with the same sign,

what do you do? (Example 1) - Add the absolute value of the numbers keep the

sign - If you are adding integers with different signs,

what do you do? (Example 2 and 3) - Subtract the absolute value of the numbers, and

keep the sign of the greater absolute value. - Absolute value how far the number is away from

zero

Example 1

- -9 -3
- Adding integers with the same sign
- Add the numbers
- Keep the sign

9 3 12

-12

-9 -3 -12

Example 2

- -15 7
- Adding integers with different signs
- Subtract the numbers
- Take the sign of the greater absolute value.

15 7 8

-15 7 -8

-15 has the greater absolute value.

Example 2

- 9 -4
- Adding integers with different signs
- Subtract the numbers
- Take the sign of the greater absolute value.

9 4 5

9 -4 5

9 has the greater absolute value.

Practice Problems

- -18 -4
- 2. 25 -10
- 3. -13 -5
- 4. -19 6
- -14 14
- 6. -6 -3 7
- 7. -5 8 -6

-22

15

-18

-13

0

-9 7

-2

3 -6

-3

Word Problems with Integers

- At 8am the temperature was -6F. At noon, the

temperature rose 9 degrees. What was the

temperature at noon? - -6 9 3F
- The temperature at noon was 3F.
- A submarine is situated 400 feet below sea level.

If it rises 125 feet, what is its new position? - -400 125 -275
- The new position of the submarine is 275 feet

below sea level.