When multiplying and dividing negative numbers, the sign of both numbers is important:
+ multiplied by + gives a positive answer
- multiplied by - gives a positive answer
+ multiplied by - gives a negative answer
- multiplied by + gives a negative answer.
The same rules apply when dividing.
For these calculations, carry out the multiplication or division as if both numbers were positive, then apply the rule afterwards.
This table can be used as a reminder:
1. Evaluate -6 x -4.
Calculate as 6 x 4 = 24; and minus multiplied by minus is a positive answer, giving +24.
2. A game scores 3 points if I win, and deducts 2 points if I lose. If I won 6 matches and lost 3, what is my score?
Calculate the winning points: +6 x +3 = +18.
Calculate the losing points: +3 x -2 which is 3 x 2 = 6, but a positive multiplied by a negative gives a negative answer: -6.
Combine the two results: 18 + -6 = 18 - 6 = 12.