Question

(10/100) Add the following decimal numbers m binary: 11 + (-15). Use 2's complement to represent negative numbers. Use a word length of 5 bits (including sign). Indicate if an overflow' occurs.

Answer 1

11 + (-15):

01011₂ + (-01111)

As you want to represent the negative number in 2's complement, now -01111 in 2's complement is: 10001₂

So, the operation is: 01011₂ + 10001₂ = 11100₂.

You can check this result by reconverting the result to decimal which should be -4.

As this is a -ve number, the resultant binary number should be 2's complemented.

2's complement of 11100 is -00100 which means -4.