# Electronics and Communication Engineering - Digital Electronics - Discussion

2.

2's complement of binary number 0101 is

 [A]. 1011 [B]. 1111 [C]. 1101 [D]. 1110

Explanation:

1's complement of 0101 is 1010 and 2's complement is 1010+1 = 1011.

 Amogh said: (Jul 6, 2014) 2's complement = 1's complement + 1.

 Sangeetha.P said: (Jul 17, 2014) 2's complement means last number is subtract by 2 then the other numbers are subtracted by 1. OTHER WAY TO FIND THE 2'S COMPLEMENT: 1. Take 1's complement. 2. And add 1 with that 1's complement answer.

 Vishdinho said: (Apr 3, 2017) @Bharathy. Put complement one time for every bit (replace 0 by 1 and 1 by 0). That means 1's complement of 0101 is 1010.

 Anusha said: (Aug 25, 2017) We have to follow 2 steps to find out the 2's complement. 1.find out 1's complement for the given num. (0's becomes 1's and 1's become 0's) 2.Add 1 to the result of 1's complement. So,(1) 1's complement of 0101 becomes 1010. (2)add 1 to this result, 1010(1's complement) 1 (adding of 1) --------------- 1011. (2's complement). It is the final answer..

 Sowmya said: (Jan 31, 2018) 0101. 1's complement is 1010. Add 1 to 1's complement is called 2's complement. i.e.,1010+1=1011.

 Harika said: (Mar 11, 2020) Answer: A. 2's complement = 1's complement+1. 1's complement means take the complement of given data.like given data is 0101 = 1010. Next 1 should be added to that complement. 1010 1 ........ 1011 So option A correct.