Signed numbers in binary use three common schemes: sign-magnitude, one’s complement, and two’s complement. For any positive value, write its binary magnitude and prefix a 0 sign bit; in sign-magnitude a negative value keeps the magnitude but switches the sign bit to 1. In one’s complement, form the negative by inverting every bit of the positive representation. In two’s complement, form the negative by taking the one’s complement and adding 1, so two’s complement equals one’s complement plus one. While positives look the same across all three, the method for negatives differs as described.