# Electronics and Communication Engineering - Digital Electronics - Discussion

Discussion Forum : Digital Electronics - Section 1 (Q.No. 2)
2.
2's complement of binary number 0101 is
1011
1111
1101
1110
Explanation:

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

Discussion:
10 comments Page 1 of 1.

Amogh said:   9 years ago
2's complement = 1's complement + 1.
(1)

Anusha said:   6 years ago
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.

1010(1's complement)
---------------
1011. (2's complement).
(1)

Palaniappan said:   3 years ago
1's complement is nothing but change all bit invert.

For example 1'complement of 1 is 0,1'complement of 0 is 1

Step1:
Here 1'complement of 0101 is 1010.

2'complement is nothing but add 1 with 1'complement.

1010 + 1 = 1011.
(1)

Bodipalh said:   2 years ago
Here is the Trick to find 2's complement.

Write the number as it is until you find the "one" after the one apply one's complement.

Example 1:
The number is 11010101 we need to find the 2's complement so find the (Start on left side) in this number the first number is one so write as it is after the one we will apply one's complement.

Ans: 00101011 this is the 2's complement.

Another example;
11010100 here the first number is zero write as it is until you find one after one apply one's complement.

00101100 This is the 2's complement of this number.
(1)

Sangeetha.p said:   9 years ago
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.

Bharathy said:   7 years ago

Vishdinho said:   7 years ago
@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.

Sowmya said:   6 years ago
0101.

1's complement is 1010.
Add 1 to 1's complement is called 2's complement.
i.e.,1010+1=1011.

Harika said:   4 years ago
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.

Krishna said:   3 years ago
What is 2's complement? Explain please.