Question

Convert the following decimal negative numbers to their 8-bit, 2’s complement formulation: -9, -63, -128

Answer 1

One way to negate a number in binary is to write out the positive version. Then going from right to left go until you reach your first "1", then every digit to the left, change "1"s to "0"s and "0"s to "1"s. In other words, flip the bits of everything left of the right most "1".

Answer 2

Example, -15 in 8 bit 2s complement.
15 is =00001111
The right most digit is a 1, so we flip everything else, so
-15 = 11110001