# How do you calculate the additive inverse of a binary number?

##### 1 Answer
May 20, 2017

Take the $1$'s complement and add $1$

#### Explanation:

The exact form depends on the word size you are using for your binary numbers.

A $1$'s complement is formed by flipping every bit - i.e. apply the "not" operator to every bit.

For example, with a $32$ bit word, the $1$'s complement of $10100$ is:

$1111$ $1111$ $1111$ $1111$ $1111$ $1111$ $1110$ $1011$

Then add $1$ to get:

$1111$ $1111$ $1111$ $1111$ $1111$ $1111$ $1110$ $1100$