Solve Division Problem: Calculate 900 ÷ 900

To solve this problem, we'll follow these steps:

• Step 1: Identify the division operation $900:900$
• Step 2: Apply the property that any non-zero number divided by itself equals 1
• Step 3: Evaluate the division to obtain the result

Now, let's work through these steps:
Step 1: Recognize that 900 is both the dividend and divisor.
Step 2: Use the property: Since 900 is not zero, the rule $a:a = 1$ where $a \neq 0$ applies here.
Step 3: Therefore, $900:900 = 1$.

This corresponds with choice 3 in the given answer choices.

Therefore, the solution to the problem is $1$.