In this section we look at how to multiply and divide negative numbers.
Worked Examples
Calculate
(−2) + (−2) + (−2) + (−2) + (−2).
Show me(−2) + (−2) + (−2) + (−2) + (−2) = −10
Fill in the missing numbers:
(−2) + (−2) + (−2) + (−2) + (−2) = ..... × (−2) = .....
Show me(−2) + (−2) + (−2) + (−2) + (−2) = 5 × (−2) = −10
In Example 1 we see that
a positive number multiplied by a negative number gives a negative answer.
This table shows what happens to the sign of the answer when positive and negative numbers are multiplied:
| × | + | – |
| + | + | – |
| – | – | + |
The same table can be used for division of positive and negative numbers.
Work out the following:
5 × (−7)
Show meFirst calculate 5 × 7 = 35.
As a positive number is multiplied by a negative number, the answer will be negative:
5 × (−7) = −35
(−8) × (−10)
Show meFirst calculate 8 × 10 = 80.
Here a negative number is multiplied by a negative number, so the answer will be positive:
(−8) × (−10) = 80
(−42) ÷ 6
Show meFirst calculate 42 ÷ 6 = 7.
As a negative number is divided by a positive number, the answer will be negative:
(−42) ÷ 6 = −7
(−88) ÷ (−8)
Show meFirst calculate 88 ÷ 8 = 11.
As a negative number is divided by a negative number, the answer will be positive:
(−88) ÷ (−8) = 11
Exercises
