1’s complement (cont’d)
Problem with 2’s complement: hard to find the negation of a number because it involves “adding 1”
This leads to 1’s complement. In 1’s complement, instead of subtracting from 100, you subtract from 99. This means that in binary, you only need to invert the bits!
The price to pay is that when we pass the 100 mark, we’ll be off by 1 (eg: -10 + 30 leads to 89 + 30 = 119. But we want 120!).
So, every time you pass the 100 mark, you need to add an extra 1.