(2) One's Complement Subtraction. The same basic steps for subtraction apply in one's

complement subtraction that are applied in two's complement subtraction, with very little change in the

procedure. To one's complement a number, just turn the ones into zeros and the zeros into ones.

01101

given

10010

one's complement

To subtract the following:

NOTE: IF THE CARRY BIT IS 1, THEN END AROUND CARRY AND ADD. THE ANSWER IS

POSITIVE. IF THE CARRY BIT IS 0, THEN ONE'S COMPLEMENT THE ANSWER. THE

ANSWER IS NEGATIVE.

Using these two numbers and subtracting with the ones complement method, we find NO CARRY BIT.

We must then one's complement the answer, and place a negative sign before the number.

10111

-1000: THE ANSWER