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

Q: Why do I need to rearrange the equation first?

Rearranging helps you isolate the unknown clearly! Instead of guessing, you transform $ 9900 - \Box = 9200 $ into $ \Box = 9900 - 9200 $, making the solution obvious.

Q: What if I just try each answer choice?

While that works, it's much slower than solving algebraically! Plus, understanding the method helps you solve similar problems even when answer choices aren't given.

Q: How do I remember which number comes first in subtraction?

Think of it as: "What do I subtract FROM the larger number?" Since 9900 - something = 9200, you subtract FROM 9900, so it's 9900 - 9200.

Q: Can I check my answer without substituting back?

Yes! Use addition to check subtraction: 9200 + 700 = 9900 ✓. If this equals the original first number, your answer is correct!

Q: What if the missing number was at the beginning instead?

For equations like $ \Box - 700 = 9200 $, you'd get $ \Box = 9200 + 700 = 9900 $. The operation switches: subtraction becomes addition!

Missing Value Equations with Large Numbers

Complete the following equation:

$9900-\Box=9200$

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Step-by-step written solution

Follow each step carefully to understand the complete solution

Understand the problem

Complete the following equation:

$9900-\Box=9200$

Step-by-step solution

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 $700$ .

Final Answer

$700$

Key Points to Remember

Essential concepts to master this topic

Rearrangement Rule: Move unknown to one side using inverse operations
Technique: Transform 9900 - □ = 9200 into □ = 9900 - 9200
Check: Substitute back: 9900 - 700 = 9200 ✓

Common Mistakes

Avoid these frequent errors

Subtracting in wrong order
Don't calculate 9200 - 9900 = -700! This gives a negative answer which doesn't make sense in the original equation. Always rearrange first: □ = 9900 - 9200 = 700.

Practice Quiz

Test your knowledge with interactive questions

Choose the correct answer:

$693+705=\text{ ?}$

FAQ

Everything you need to know about this question

Why do I need to rearrange the equation first?

Rearranging helps you isolate the unknown clearly! Instead of guessing, you transform $9900 - \Box = 9200$ into $\Box = 9900 - 9200$ , making the solution obvious.

What if I just try each answer choice?

While that works, it's much slower than solving algebraically! Plus, understanding the method helps you solve similar problems even when answer choices aren't given.

How do I remember which number comes first in subtraction?

Think of it as: "What do I subtract FROM the larger number?" Since 9900 - something = 9200, you subtract FROM 9900, so it's 9900 - 9200.

Can I check my answer without substituting back?

Yes! Use addition to check subtraction: 9200 + 700 = 9900 ✓. If this equals the original first number, your answer is correct!

What if the missing number was at the beginning instead?

For equations like $\Box - 700 = 9200$ , you'd get $\Box = 9200 + 700 = 9900$ . The operation switches: subtraction becomes addition!

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