## Wow, this works! We can add numbers without thinking about their sign! Let’s do this in binary.

## Example with 4 bits. Instead of using decimal 100 as 0 mark, we use binary 10000. So -I is represented by 10000 - I. Everything is the same just that we do things in binary.

## Shortcut for computing 2’s complement.

- 10000 - I = (1111 + 1) - I = (1111 - I) + 1
- What does 1111 - A mean? It’s the same as inverting...
- So, to take 2’s complement: invert bits and add 1.

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