# Multiply Negative Numbers

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

## Formula

### Formula

If multiplying same signed numbers,

the result is plus.

(+)⋅(+) = (+)

(-)⋅(-) = (+)

If multiplying different signed numbers,

the result is minus.

(+)⋅(-) = (-)

(-)⋅(+) = (-)

## Example 1

### Example

### Solution

-5 is minus.

-4 is minus.

So -5⋅(-4) is minus times minus.

So write plus.

5 times 4 is 20.

So write 20.

So +20 is the answer.

Or you can simply write 20.

## Example 2

### Example

### Solution

3 is plus.

-7 is minus.

So 3⋅(-7) is plus times minus.

So write minus.

3 times 7 is 21.

So write 21.

So -21 is the answer.

## Example 3

### Example

### Solution

-9 is minus.

2 is plus.

So -9⋅2 is minus times plus.

So write minus.

9 times 2 is 18.

So write 18.

So -18 is the answer.