Compute binary addition: 11 plus 01.

• A. 10
• B. 11
• C. 100
• D. 101

Answer: (C)

Binary addition works like decimal addition but with base 2. You add from the rightmost bit, carrying when the sum reaches 2. For 11 and 01, the rightmost column is 1 plus 1 equals 10, so write 0 and carry 1. In the next column, 1 plus 0 plus the carried 1 equals 10 again, so write 0 and carry 1. There’s a final carry, giving a new leftmost 1, so the result is 100. This also matches converting to decimal: 11₂ is 3 and 01₂ is 1, total 4, which is 100₂.