# Electronics - Arithmetic Operations and Circuits - Discussion

Discussion Forum : Arithmetic Operations and Circuits - General Questions (Q.No. 11)
11.
Binary subtraction of a decimal 15 from 43 will utilize which two's complement?
101011
110000
011100
110001
Explanation:
No answer description is available. Let's discuss.
Discussion:
10 comments Page 1 of 1.

Yamuna said:   3 years ago
Still, I didn't understand. Please, can you explain once?

Nisha said:   5 years ago
The question is that which 2's complement utilize.

And it is 15. It is subtracted and we make two's complement of it which is 110001.

SPS said:   6 years ago

Two's complement is nothing but the complement of given no plus 1.

Jaskaran singh(jass) said:   6 years ago
Please explain, what is mean of two's complement?

Chethan said:   9 years ago
Yea @Rathi, you are right, Thanks for the meaning of the question.

Rathi said:   9 years ago
@Brajendra.

Your way of subtraction is correct. But in the Question "will utilize which two's complement".

I think they ask value of the 2's complement which is used in that subtraction. So 2's complement of 15 = 1 1 0 0 0 1.

Brajendra Kumar Mishra said:   9 years ago
I think answer will be (C).

43 = 1 0 1 0 1 1.
15 = 0 0 1 1 1 1.

Take the 2's complement of 15 =1 1 0 0 0 1.

Then add this value with binary equivalent of 43.

Will get,

1 0 1 0 1 1
+1 1 0 0 0 1
=1 0 1 1 1 0 0.

Then discard the carry output you will get 011100 so option will be (C).
We can verify it by taking simply 43 - 15 = 28.

When you will convert option C in decimal number that will give the correct answer that is '28'.

So option C is the correct answer.

Sourav said:   9 years ago
I don't agree with your answer @Nikhil, 2's comp can be made up after 1's compliment but you did it in a wrong way to make the answer correct.

Nikhil said:   10 years ago
43 is 101011 --- (1).
15 is 1111 ----- (2).

Subtract (1)-(2)=110000.
And 2's comp of 110000 is 110001.