1. Multiplying and Dividing Integers
What will the sign be?

2. Multiplication You can think of multiplication as repeated addition
3 x 2 = = 6
3 x (–2) = (–2) + (–2) + (–2) = –6

3. Random Examples 4 x 5 = 20 -4 x 5 = -20 4 x -5 = -20 -4 x -5 = 20
What do we notice about the signs? Is there anything you can conclude?

4. Rules MULTIPLYING INTEGERS If the signs are: Your answer will be:
the same
positive
different
negative

5. Examples 3 x 12 =36 4 x -12 -1 x 7 = - 48 4(-3) -3(-5) = -7 13(-2)
= - 12
= 15
= - 26

6. Division
Multiplication and division are inverse operations. They “undo” each other. You can use this fact to discover the rules for division of integers.

7. Examples 4 • (–2) = –8 –8 ÷ (–2) = 4 –4 • (–2) = 8 8 ÷ (–2) = –4
Course 2
Examples
4 • (–2) = –8
–8 ÷ (–2) = 4
Same signs
Positive
–4 • (–2) = 8
8 ÷ (–2) = –4
Different signs
Negative
The rule for division is like the rule for multiplication!

8. Rules DIVIDING INTEGERS If the signs are: Your answer will be:
the same
positive
different
negative

9. Examples 15 ÷ 5 32 ÷ -4 -12 ÷ 3 -4 ÷ -2 27 ÷-3 -125 ÷ -5 =3 = - 8 = -4=2
= - 9
= 25