1. Objective The student will be able to:
multiply rational numbers.

2. Multiplying Rules
1) If the numbers have the same signs then the product is positive.
(-7) • (-4) = 28
2) If the numbers have different signs then the product is negative.
(-7) • 4 = -28

3. Multiplying fractions:
Examples
1) (3x)(-8y)
-24xy 2)
Write both numbers as a fraction.
Cross-cancel if possible.
Multiplying fractions:
top # • top #
Bottom # • bottom# =
-16

4. When multiplying two negative numbers, the product is negative.
True
False
Answer Now

5. When multiplying a negative number and a positive number, use the sign of the larger number.
True
False
Answer Now

6. 3) = =

7. Multiply: (-3)(4)(-2)(-3)72
-72 36
-36
Answer Now

8. an easy way to determine the sign of the answer
When you have an odd number of negatives, the answer is negative.
When you have an even number of negatives, the answer is positive.
4) (-2)(-8)(3)(-10)
Do you have an even or odd number of negative signs?
3 negative signs -> Odd -> answer is negative
-480

9. Positive or negative answer? Positive - even # of negative signs (4)
Last one! 5)
Positive or negative answer?
Positive - even # of negative signs (4)
Write all numbers as fractions and multiply.
=12

10. What is the sign of the product of (-3)(-4)(-5)(0)(-1)(-6)(-91)?
Positive
Negative
Zero
Huh?
Answer Now