Multiplying Integers (Jump to: Lecture | Video )

3 * 9 = ?

How do we solve the above equation? What it's really saying is that we have 3 of the number 9, like this:

9 + 9 + 9 = 27

When we multiply two positive numbers, the answer is always positive.

(-3) * (-9) = 27

When we multiply two negative numbers, the answer is always positive.

(-3) * 9 = -27

3 * (-9) = -27

When we multiply a positive number and a negative number, the answer is always negative.