Multiplying and Dividing Signed Numbers
Now, let’s review multiplication and division of signed numbers.
To multiply or divide two signed numbers, follow these steps:
Step 1 Ignore the signs and do the multiplication or division.
Step 2 Attach a sign to the product as follows:
| • If the original numbers have the same sign, attach a positive sign.
|
2 · 3 = 6
-2 · (-3) = 6 |
| • If the original numbers have different signs, attach a
negative sign. |
-2 · 3 = -6
2 · (-3) = -6 |
Example 1
Find the products:
a. -5 · 3
b. -6(-7)
c. 8 × (-4)
d. 0 · (-2)
Solution
| a. -5
· 3 = -15
b. -6(-7)
= 42
c. 8 × (-4)
= -32
d. 0 · (-2)
= 0 |
The signs are different so the product is negative.
The signs are the same so the product is positive.
The signs are different so the product is negative.
Zero has no sign (it is neither negative nor
positive). |
Example 2
Find the quotients:
Solution
| a. -18 ÷ 3 =
-6 b. -8 ÷
(-4) = 2
c.
d.
e.
is undefined. |
The signs are different so the quotient is negative.
The signs are the same so the quotient is positive.
The signs are different so the quotient is negative.
Zero has no sign (it is neither positive nor
negative).
Division by 0 is not allowed. |
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