Binary subtraction is a mathematical operation where one binary number is subtracted from another. Standard techniques adopted for decimal numbers are used to do the deduction. That is, the subtraction of each bit pair takes place from right to left.
Something called the "two's complement" of the number that is subtracted has to be calculated first in order to compute a binary subtraction. The two's complement is obtained by replacing the ones with zeros and the zeros with ones in the given binary number. Following the rules of binary addition, one should then add one to the new number to find the two's complement. It is only after doing this that the binary subtraction can be computed the same way as decimal numbers.