Calculate -3 + 3 using Two's Complement and the Sign and Magnitude Method. Which works correctly?

Using the Two's complement notation of -3 and 3 (11111101 and 00000011), binary addition will return 100000000 which has an overflow error, so the 9th bit is ignored giving a value of 00000000 which is equal to 0. We know this is correct since it matches the true value of -3 + 3. Using the sign and magnitude nation of -3 and 3 (10000011 and 00000011), binary addition will return 10000110 which is equal to 134. Clearly this isn't correct and we can see that Sign and Magnitude method doesn't work with binary arithmetic. Informative poster: https://drive.google.com/open?id=1cDdWKai0_t8wjGrcmaI8pjDV2aBnd0Qn