The result of binary subtraction between 1001 and 101 is :

Binary subtraction follows specific rules: 0 - 0 = 0, 1 - 1 = 0, 1 - 0 = 1, and 0 - 1 = 1 (with a borrow of 1 from the next higher bit). To solve 1001 - 101:

• Step 1: Rightmost column (2⁰): 1 - 1 = 0.
• Step 2: Second column (2¹): 0 - 0 = 0.
• Step 3: Third column (2²): 0 - 1. We borrow from the fourth column (2³). The 1 at 2³ becomes 0, and the 0 at 2² becomes 10₂ (which is 2 in decimal). Now, 2 - 1 = 1.
• Step 4: The result is 100.

Verification using decimal conversion: 1001₂ is 9₁₀ and 101₂ is 5₁₀. Since 9 - 5 = 4, and 4 in binary is 100₂, the answer is confirmed.