Electronics and Communication Engineering - Digital Electronics - Discussion

Explanation and answer are wrong.

Number with Most Significant digital represents a negative number i.e.
-1*128+1*64+1*32+0*16+0*8+1*4+0*2+1*1.
=-128+64+32+4+1=-27 (which is original number).

Now, 2's complement of the number will be:
1's C: 00011010.
2's C: 00011011.

Binary Equivalent: 16+8+2+1=27 (which is required answer).

The Answers Should be C.

I think in any condition the 1st bit indicates sign of that number and 0 indicates positive sign and 1 indicates negative sign.

I can't understand it clearly, Please give me the explanation in detail.

Is the 1's complement and 2's complement are the complement each other?

Because the procedure is same, if we find the 2's complement we use the same procedure and here also use the same procedure.

Carry 1 indicates a positive number.
Carry 0 indicates a negative number.
Hence after adding 1 to the complement, the carry remains 0.

I am not getting this, please anyone explain me.

Please understand the question?
The question is saying that the given binary number 11100101 is in already 2's complement form, then how can we write 11100101 in decimal format?

Ans: Left most digit is 1 means it should be a negative number (A/C to question)
1= -ve
0= +ve

step_1------->substract 1 from 11100101 to get 1's complement form
we will get 1's form = 11100100.

step_2--------> Now reverse each digit of 11100100 to get original number in binary
we will get 00011011=27.

step_3--------> so answer will be -27.

Negative numbers are always represented in 2's compliment form. That's why the original no must be negative.

Why negative sign comes?