Electronics - Arithmetic Operations and Circuits - Discussion

43's two's complement is 010001.

15's two's complement is 0001.

Binary subtraction is 010000 may I know what is wrong in my answer.

43 is 101011 --- (1).
15 is 1111 ----- (2).

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

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.

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.

@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.

So D is Correct Answer.

Yea @Rathi, you are right, Thanks for the meaning of the question.

Please explain, what is mean of two's complement?

@Jaskaran.

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

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.

Still, I didn't understand. Please, can you explain once?