0001 0110 (correct)
The number to be subtracted is negated by the usual means (reflect the bits, add one):
0001 1011 → 1110 0101
Then the "binary addition algorithm" is used:
11100 001 0011 0001 = 4910 1110 0101 = -2710 --------- ----- 0001 0110 2210
Since the carry into the most significant column is the same as the carry out of that column, the result is correct. We are getting quite a bit of use out of the "binary addition algorithm". It is used to:
It can't be used directly to subtract integers represented in unsigned binary. (If both unsigned integers are small enough, the one being subtracted can be represented as a two's complement negative, and then the algorithm can be used.) In the programming language Java all integers (int and long) are represented using two's complement.