The answer is -22. As you can see from this example, when you are dealing with a negative answer, you

must find two complements. The extra-order 1 must be generated before the end-around-carry can be

performed. If there is no extra-order 1, the answer is a negative number.

d. Binary Complement. A digital computer that uses the binary number system will use the binary

complement system. In the binary system, the two methods are: 2's complement (no end-around-carry)

and 1's complement (end-around-carry). First consideration will be given to finding the 2's complement

of any binary number. The 2's complement is performed by changing each digit to is opposite and adding

1 to the least significant digit (LSD).

Finding the 2's complement of any binary number can be simplified even further by starting at the least

significant bit (binary digit) position and inspecting each bit position for a 1. The least significant 1 and

all 0s to its right are copied without change. All bits to the left of the least significant 1 are changed. Of

course, identical results are obtained with the two methods.

(1) Binary Complement Subtraction.

Binary complement subtraction is performed by

complementing the subtrahend and adding. The method of 2's complement for subtraction is illustrated

below.