# Inverse

Inverse means the opposite in effect. The reverse of.

Inverse has many meanings in mathematics. Here are a few.

## The Inverse of Adding is Subtracting

Adding moves us one way, subtracting moves us the opposite way.

Example: 20 + 9 = 29 can be reversed by 29 − 9 = 20 (back to where we started)

And the other way around:

Example: 15 − 3 = 12 can be reversed by 12 + 3 = 15 (back to where we started)

The additive inverse is what we add to a number to get zero.

### Example: The additive inverse of −5 is +5, because −5 + 5 = 0.

Another example: the additive inverse of +7 is −7.

## The Inverse of Multiplying is Dividing

Multiplying can be "undone" by dividing.

Example: 5 × 9 = 45 can be reversed by 45 / 9 = 5

It works the other way around too, dividing can be undone by multiplying.

Example: 10 / 2 = 5 can be reversed by 5 × 2 = 10

## Multiplicative Inverse

The multiplicative inverse is what we multiply a number by to get 1.

It is the reciprocal of a number.

### But Not With 0

You can't divide by 0, so don't try!