In this lesson on algebra negative numbers are covered. Get information and negative numbers practice here.
There are two rules for multiplying and dividing numbers:
That's it! You multiply or divide as normal, then use these rules to determine whether the answer is positive or negative. For instance, take this problem, -3 ⋅ -4. 3 ⋅ 4 is 12. Because both numbers we multiplied were negative, the answer is positive: 12.
-3 ⋅ -4 = 12
On the other hand, if we were to multiply 3 ⋅ -4, we'd get a different answer:
3 ⋅ -4 = -12
Again, 3 ⋅ 4 is 12. But because one of our multiples is negative and the other is positive, our answer must also be negative: -12.
It works the same way for division. -40 / -10 is 4 because -40 and -10 are both negatives. However, -40 / 10 is -4 because one number is negative and the other is positive.
Curious to learn more? This Khan Academy video explains why this works the way it does.
Want even more practice? Try out a short assessment to test your skills by clicking the link below: