What is the sum of binary numbers 01101101 and 00111100?

• A. 010101001
• B. 010101000
• C. 001010101
• D. 010101010

Answer: (A)

Binary addition adds digits from right to left, carrying when the sum reaches 2 or more. Adding 01101101 and 00111100 step by step gives 10101001 in 8-bit form. Here’s the carry flow: 1+0=1 (no carry), 0+0=0 (no carry), 1+1=2 → write 0, carry 1, then 1+1+carry1=3 → write 1, carry 1, 0+1+carry1=2 → write 0, carry 1, 1+1+carry1=3 → write 1, carry 1, 1+0+carry1=2 → write 0, carry 1, final 0+0+carry1=1 → write 1 with no carry. So the 8-bit result is 10101001. If you display it as 9 bits, you can prepend a leading zero to get 010101001, which matches the given option. In decimal terms, 109 + 60 = 169, and 169 is 10101001 in binary.