Two's complement in 5 minutes

My quick notes: - To negate a number: flip every bit, then add 1. - The leftmost bit tells you the sign (1 = negative). - The range for n bits is -2^(n-1) to 2^(n-1) - 1. - Overflow happens when adding two numbers of the same sign gives a result of the opposite sign. - Sign extension: copy the sign bit to the left to widen a number without changing its value.