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 5 of 6.

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

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.

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.

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

Santhoshstebin said:   1 decade ago
0 mean positive value 1.
1 mean negative value -1.

Akash choudhary said:   1 decade ago
In 2's complement if first digit from left is 1 then it is a -ve number else 0 then +ve number.

Suman said:   1 decade ago
How we can we get 16+8+2+1?

RAJESH SHAKYA said:   1 decade ago
How can decide fist bit (sign bit or MSB)?

Jitendra said:   1 decade ago
-ve sign is problem here.

According to first no. it should be +ve.

Derepika said:   1 decade ago
How 16+8+2+1 comes from 00011011 in hexadecimal.


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