Another way to represent negative numbers is to use the compliment of
one less than it. What this means is that if we want -1 we store it as
the compliment of one less than 1 or 0. The compliment means we flips all
the bits. So since 0 has 32 0's, its compliment has all 1's.
The reason that this represents -1 is clear when we add 1 to it. Since all the
bits are 1, adding one leads to 233, setting the 33rd bit to one which is
outside the 32 bits that we have, with the 32 bits equal to zero. So adding one to
this leads to zero which is the same as -1. Similarly we can store -2 as
the compliment of 1, with all the 32 bits set to 1 except the 1st one.