Now let's consider how we would solve our problem of subtracting 1_{10} from 7_{10} using 2's complement.

0111 (7)  0001  (1) 

0001 > 1110 1 1111 

0111 (7) + 1111 +(1) 10110 (?) 

0111 (7)  0001  (1) 0110 (6) 
The animation below demonstrates how to subtract the 5bit binary numbers 01101_{2} and 01001_{2} using 2's complement representation. Click on the "Start Tutorial" button to view the animation.
Let's review the steps for subtracting x from y with an nbit 2's complement representation.
 Negate x using 2's complement.
 Reverse all the bits in x.
 Add 1 to form x.
 Add x and y.
 Discard any bits greater than n.
Now go back and compare these steps with the steps for 1's complement subtraction. Notice that with 1's complement, you must check for an overflow bit each time you perform a subtraction. If the result has an overflow, you need to add the extra bit to your result to obtain the correct answer. However, with 2's complement, we only need to ignore this extra bit. No other computations are required to find the correct answer. This makes 2's complement a more efficient way of representing signed numbers and performing binary subtraction.