Question

what's the 2's compliment of the hexdecimal number ACBD ?

Select one:

a.

-21315

b.

21315

c.

-21335

d.

21335

Answer 1

a)  -21315

Explanation:
-------------
Hexadecimal     Binary
    0           0000
    1           0001
    2           0010
    3           0011
    4           0100
    5           0101
    6           0110
    7           0111
    8           1000
    9           1001
    A           1010
    B           1011
    C           1100
    D           1101
    E           1110
    F           1111
Use this table to convert from hexadecimal to binary
Converting ACBD to binary
A => 1010
C => 1100
B => 1011
D => 1101
So, in binary ACBD is 1010110010111101

Now converting ACBD to decimal
since left most bit is 1, this number is negative number.
so, follow these steps below to convert this into a decimal value.
I. first flip all the bits. Flip all 0's to 1 and all 1's to 0.
   1010110010111101 is flipped to 0101001101000010
II. Add 1 to above result
0101001101000010 + 1 = 0101001101000011
III. Now convert this result to decimal value
Converting 101001101000011 to decimal
101001101000011
=> 1x2^14+0x2^13+1x2^12+0x2^11+0x2^10+1x2^9+1x2^8+0x2^7+1x2^6+0x2^5+0x2^4+0x2^3+0x2^2+1x2^1+1x2^0
=> 1x16384+0x8192+1x4096+0x2048+0x1024+1x512+1x256+0x128+1x64+0x32+0x16+0x8+0x4+1x2+1x1
=> 16384+0+4096+0+0+512+256+0+64+0+0+0+0+2+1
=> 21315
Answer: -21315