Electronics and Communication Engineering - Digital Electronics - Discussion

Discussion Forum : Digital Electronics - Section 1 (Q.No. 7)
7.
In 2's complement representation the number 11100101 represents the decimal number
+37
-31
+27
-27
Answer: Option
Explanation:

A = 11100101. Therefore A = 00011010 and A' = A + 1 = 00011011 = 16 + 8 + 2 + 1 = 27. Therefore A = -27.

Discussion:
54 comments Page 2 of 6.

Naina said:   1 decade ago
I don't understand this step 16+8+2+1.

Sudha said:   1 decade ago
00011011 = 00011011.

= 0(2^7)+0(2^6 )+0(2^5)+1(2^4 )+1(2^3)+0(2^2)+1(2^1)+1(2^0).

= 16+8+2+1 = -27.

Sai said:   1 decade ago
Given A = 11100101.

2's comp A' = A + 1 = 00011011.

Why did you consider from A? Why didn't you consider from A' I mean sign.

Ashok said:   1 decade ago
I don't understand 16+8+2+1.

Geetha adainjan said:   1 decade ago
2's com -11100101. Then 1's com is 11100101-1=1100100.

Then the required binary no is 0011011. According to binary to decimal conversion the position value is 128, 64, 32, 16, 8, 4, 2, 1 here binary 1 is present in 16+8+2+1=27.

E&tc group D.Y. Patil ambi pune said:   1 decade ago
-(2^4=16, 2^3=8, 2^1=2, 2^0=1) = -27.

Anshika said:   10 years ago
How come it is -ve sign. It should be +ve?

Can anyone explain me?

B.Mallesh goud said:   10 years ago
Why we use -ve sign instead of +ve sign?

Sita said:   10 years ago
In the given binary form msb bit is 1 should keep '-' sign. Msb bit is 0 then you should keep positive sign.

Aslam said:   10 years ago
They asked decimal equivalent of 2's complement of 11100101 which is 00011011 here MSB is 0, hence +27.


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