subsbroct the following binary numbers using
1s and 2s complement method 11101 - 10101.
Answers
Answer:
The steps to be followed in subtraction by 1’s complement are:
The steps to be followed in subtraction by 1’s complement are:
i) To write down 1’s complement of the subtrahend.
ii) To add this with the minuend.
iii) If the result of addition has a carry over then it is dropped and an 1 is added in the last bit.
iv) If there is no carry over, then 1’s complement of the result of addition is obtained to get the final result and it is negative.
Evaluate:
(i) 11101 – 10101
Solution:
1’s complement of 10101 is 01010. Hence
Minuend - 1 1 1 0 1
1’s complement of subtrahend - 0 1 0 1 0
Carry over - 1 0 0 1 1 1
+ 1
0 1 0 0 0
The required difference is 1000
Subtraction by 2’s Complement
The operation is carried out by means of the following steps:
(i) At first, 2’s complement of the subtrahend is found.
(ii) Then it is added to the minuend.
(iii) If the final carry over of the sum is 1, it is dropped and the result is positive.
(iv) If there is no carry over, the two’s complement of the sum will be the result and it is negative.
Evaluate:
(i) 11101 - 10101
Solution:
2’s complement of 10101 is (01010 + 1) i.e.01011. Adding this with the minuend.
1 1 1 0 1 Minuend
0 1 0 1 1 2’s complement of subtrahend
Carry over 1 0 1 0 0 0 Result of addition
After dropping the carry over we get the result of subtraction to be 1000.