Solve the Equation: Finding the Missing Number in 9900 - □ = 9200

To solve this problem, we'll first rearrange the equation to isolate the missing number:

• Step 1: Start with the given equation $9900 - \Box = 9200$.
• Step 2: Rearrange to solve for the missing number $\Box$: $\Box = 9900 - 9200$.
• Step 3: Perform the subtraction: $9900 - 9200 = 700$.

Thus, the missing number is $700$.

The correct choice that corresponds to this solution is choice 3, which is $700$.