101 - 11 = 10. Indeed, using the borrow method, we see the last digit of the result must be 1 - 1 = 0. Then to perform 0 - 1 we need to borrow 1: 0 - 1 = 10 - 1 = 1. And that's it: since we've borrowed, no digits are left. Hence, the result is 10.

There are at least three methods you can use to subtract binary numbers:

• Borrow method – align the numbers and subtract by borrowing as always, remembering that 10 - 1 resolves to 1.
• Complement method – the idea is to replace the subtracted number with its complement and add the two numbers. Remember to omit the leading 1 from the result!
• Conversion method – convert your binary numbers to decimals, subtract, and then transform them back to binary. Effective for small numbers.

To determine the complement of a binary number in the 8-bit system, follow these steps:

1. Make sure your binary has 8 digits. If it has fewer, add some leading zeros.
2. Replace every digit with the opposite one: 0→1 and 1→0.
3. Increase the number by 1. That's it!