Which is the binary representation of 11?

• A. 00011010
• B. 00101111
• C. 00001011
• D. 00110000

Answer: (C)

To convert a decimal number to binary, break it down into sums of powers of two. 11 equals 8 + 2 + 1, so the binary representation has 1s in the 8, 2, and 1 positions and 0s elsewhere. When written as an 8-bit byte, that becomes 00001011: zeros padding the higher bits, then 1 for 8, 0 for 4, 1 for 2, and 1 for 1. The leading zeros don’t change the value; they just fit the number into a full byte. The other patterns represent different sums (for example, 26, 47, and 48), so they aren’t 11.