Compute 0110 + 0011 in 4-bit binary.

• A. 0000
• B. 0001
• C. 1001
• D. 1000

Answer: (C)

Binary addition adds bit by bit from right to left, carrying when the sum of bits is 2 or more. For 0110 plus 0011, align and add:

Rightmost bit: 0 + 1 = 1

Next: 1 + 1 = 0 with a carry of 1

Next: 1 + 0 plus the carried 1 = 0 with a carry of 1

Leftmost: 0 + 0 plus the carried 1 = 1

So the 4-bit result is 1001, which is 9 in decimal. That’s why this option is correct. The other patterns correspond to 0, 1, and 8, so they don’t match the sum. There’s no overflow for this addition within 4 bits.