# Multiply Negative Numbers

How to multiply minus numbers (negative numbers): formula, 3 examples, and their solutions.

## Formula

If multiplying same signed numbers,

the result is plus.

(+)⋅(+) = (+)

(-)⋅(-) = (+)

If multiplying different signed numbers,

the result is minus.

(+)⋅(-) = (-)

(-)⋅(+) = (-)

## Example-5⋅(-4)

Solution

Solution (Detail)

-5⋅(-4) is (-)⋅(-).

So write (+).

5⋅4 = 20

So +20 is the answer.

Or you can simply write 20.

## Example3⋅(-7)

Solution

Solution (Detail)

3⋅(-7) is (+)⋅(-).

So write (-).

3⋅7 = 21

So -21 is the answer.

## Example-9⋅2

Solution

Solution (Detail)

-9⋅2 is (-)⋅(+).

So write (-).

9⋅2 = 18

So -18 is the answer.