Solve the Subtraction Equation: 3609 - □ = 9

To solve this subtraction problem, follow these steps:

• Step 1: Identify the equation given in the problem: $3609 - \Box = 9$.
• Step 2: Recognize that $\Box$ is the number that needs to be subtracted from 3609 to result in 9.
• Step 3: Rearrange the equation to isolate $\Box$:
• We use the subtraction property: $\Box = 3609 - 9$.
• Step 4: Perform the subtraction:
• Calculate $3609 - 9 = 3600$.
• Step 5: Verify the calculation:
• Double-check the subtraction to ensure accuracy: if 3600 is subtracted from 3609, the remainder is indeed 9.
• Step 6: Review the choices to see which matches the calculated solution.
• The correct choice is 3600, which is option 4.

Therefore, the solution to the problem is $\Box = 3600$.