Hi I am trying to learn how to complete 2's complementation form.  I
currently have this task to complete and have given it my best to
figure it out but really need to see if I am correct.  Can someone
please show the workings for the below question:

Perform the following binary arithmetic, showing all carry/borrow bits
and stating validity for both unsigned and 2?s complement data:
1. % 1011 0011 + % 0110 1100 
2. % 1001 0110 ? % 1010 0011 
3. % 0011 1011 ? % 0001 1010

Perform the following binary arithmetic, showing all carry/borrow bits
and stating validity for both unsigned and 2?s complement data:
1. % 1011 0011 + % 0110 1100 
2. % 1001 0110 ? % 1010 0011 
3. % 0011 1011 ? % 0001 1010

To check validity of 2's complement numbers, if Number A is positive
and Number B is negative, you can't get overflow/underflow, so it's
valid. if Number A is negative and Number B is negative, check the
sign bit of the answer. If it's not 1 (ie negative) then you've had
underflow. If Number A is postive and Number B is postive, and the
sign bit of the answer is 1, then you've had overflow. As far as
calculating 2's complement numbers. It's easier to just make
subtraction addition. To negate a 2's complement numbers, invert all
bits and add 1. So for 2. 1001 0110 - 1010 0011 = 1001 0110 + 0101
1100 + 0000 0001.