Can anyone help me regarding

Question

Hello everybody..
Can anyone help me regarding the following question?
Consider a machine that performs calculations 4 bits at a time. Eight-bit 2's complement numbers can be added by adding the four least significant bits, followed by the four most significant bits. The leftmost bit is used for the sign, as usual. With 8 bits for each number, add -4 and -6, using 4-bit binary 2's complement arithmetic. Did overflow occur?
Did carry occur? Verify your numeric result.

Answer 1

No Need Of Your Help, Thank You You Sleepy Guys
Here is the answers:
Decimal: 20      
     Binary: 10100
Binary (8 bits): 0001 0100
Machine performance: 0001 and 0100 (i.e. 4 bits at a time)
Eight-bit 2�s complement numbers:
          00010100
          11101011 (1�s complement)
               +1
          11011100 (2�s complement)
Machine performance: 1100 and 1101 (4 bits each)
          1100 (i)
          1101 (ii)
          11001
          00011001 (8 bits)     
For -4 = 1111 1100, (8 bits 2�s complement of 4) and
For -6 = 1111 1010 (8 bits 2�s complement of 6)
For (i)
               0000 1100
     Adding (-4)     1111 1100
          10000 1000
               0000 1100
Adding (-6)     1111 1010
     10000 0110
For (ii)
                    0000 1101
          Adding (-4)     1111 1100
               10000 1001
                    0000 1101
Adding (-6)     1111 1010
          10000 0111
So, from the above points (i) and (ii), we can find out that an overflow does occur and a carry does exist.
Ha Ha,