Explanation

• In binary notation, the decimal number 9 is represented as 1001.
• Here's the binary conversion:
• 9 = 1 × 2^3 + 0 × 2^2 + 0 × 2^1 + 1 × 2^0
• = 1 × 8 + 0 × 4 + 0 × 2 + 1 × 1
• = 8 + 0 + 0 + 1
• = 1001 (in binary)