1. Grade 9 Integer Review
Review Day 1

2. Can be visualized on a number line:
What is an Integer?
A whole number that is either greater than 0 (positive) or less than 0 (negative)
Can be visualized on a number line:

3. What are Opposites?
Two integers the same distance from the origin, but on different sides of zero
Every positive integer has a negative integer an equal distance from the origin
Example: The opposite of 6 is -6
Example: The opposite of -2 is 2

4. What is Absolute Value?
Distance a number is from zero on a number line (always a positive number)
Indicated by two vertical lines | |
Every number has an absolute value
Opposites have the same absolute values since they are the same distance from zero
Example: |-8| = 8 and |8| = 8
Example: |50| = 50 and |-50| = 50

5. What Can We Do to Integers?
Integers are numbers, so we can add, subtract, multiply, and divide them
Each operation has different rules to follow

6. First Remove Double Signs!!
Eg: (-3) + (-4)

7. Adding Rules – Same Signs
If the integers have the SAME signs: ADD the numbers & keep the same sign!
Positive + Positive = Positive Answer
Negative + Negative = Negative Answer

8. Adding (Same Signs) - Examples
# (-10)
- Change the double sign + (-) to a (-)
- Same signs - add and keep sign!
= -13
# (8)
- Same sign so add and keep sign!
= 14

9. Adding Rules – Different Signs
If the integers have DIFFERENT signs: SUBTRACT the numbers & use sign of the BIGGER( further from zero) number!
Bigger # is Positive = Positive Answer
Bigger # is Negative = Negative Answer

10. Adding (Different Signs) - Examples
# (7)
- Subtract the numbers
- Keep the sign of the number furthest from zero (bigger number)
= -6
# (-8)
- Keep the sign of the number furthest from zero (bigger number)
= +15

11. Subtracting Rules Make sure to change any double signs
Follow the rules for ADDITION:
-SAME signs: Add & keep the same sign DIFFERENT signs: Subtract & use sign of bigger #

12. Subtracting - Examples
#1. -5 – -12
- Change double signs to a +
- Subtract the two numbers and keep the sign of the number further from zero (bigger number)
= +7
#2. 9 – 23
= -14 d

13. Multiplying Rules Multiply the numbers like usual
If the integers have the SAME signs: ANSWER will be POSITIVE
If the integers have DIFFERENT signs: ANSWER will be NEGATIVE

14. Multiplying - Examples
# · (-5)
- negative times negative = +
= +15
#2. -9 · (+10)
- Negative times a positive = (-)

15. Dividing Rules Divide the numbers like usual
If the integers have the SAME signs: ANSWER will be POSITIVE
If the integers have DIFFERENT signs: ANSWER will be NEGATIVE

16. Dividing - Examples #1. -33 ÷ (-3) - Negative divide negative = +
# ÷ (-3)
- Negative divide negative = +
= +11
# ÷ (+10)
- Negative divide a positive = (-)
= -9

17. Solve the following problems:
Mixed Practice
Solve the following problems:
-18
7 × -4
-28
(-19) 9
-35 ÷ -7 5
-10
-32

18. Review Visit the website below for additional information on integers:
lessons/S1U1L10GL.html