Solve the Addition Equation: 1000 + □ = 1001

Q: Why do I subtract 1000 from both sides?

When you have $ 1000 + \Box = 1001 $, subtracting 1000 from both sides keeps the equation balanced. The left side becomes just $ \Box $, and the right side becomes $ 1001 - 1000 = 1 $.

Q: How is this different from regular subtraction problems?

In regular subtraction like $ 1001 - 1000 $, you already know both numbers. Here, you're working backwards from an addition fact to find the missing piece!

Q: What if the missing number was bigger?

The method stays the same! For example, in $ 500 + \Box = 1001 $, you'd calculate $ \Box = 1001 - 500 = 501 $. Always subtract the known addend from the sum.

Q: Can I check my answer a different way?

Yes! You can also think about it as: "What do I add to 1000 to get 1001?" Since 1000 and 1001 are consecutive numbers, the difference is always 1.

Q: Why are the other answer choices wrong?

10: 1000 + 10 = 1010 (too big)100: 1000 + 100 = 1100 (way too big)1000: 1000 + 1000 = 2000 (much too big)Only 1 gives us exactly 1001!

Addition Equations with Large Numbers

Complete the following equation:

$1000+\Box=1001$

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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:

$1000+\Box=1001$

Step-by-step solution

To solve the equation $1000 + \Box = 1001$ , we need to determine what number, when added to 1000, results in 1001.

Let's work through the solution with a simple subtraction method:

Step 1: We know that $1000 + \Box = 1001$ , and we need to find $\Box$ .
Step 2: We can rearrange this equation to find $\Box$ by subtracting 1000 from both sides of the equation. This gives:

$\Box = 1001 - 1000$

Step 3: Perform the subtraction:

$\Box = 1$

Therefore, the missing number is $1$ .

Final Answer

$1$

Key Points to Remember

Essential concepts to master this topic

Rule: Use subtraction to find the missing addend in equations
Technique: Transform 1000 + □ = 1001 into □ = 1001 - 1000
Check: Substitute back: 1000 + 1 = 1001 confirms our answer ✓

Common Mistakes

Avoid these frequent errors

Adding instead of subtracting to solve
Don't try to find □ by doing 1000 + 1001 = 2001! This gives the wrong operation and a massive incorrect answer. Always subtract the known addend from the sum to find the missing addend.

Practice Quiz

Test your knowledge with interactive questions

Solve the exercise using the structure table below:

$$ 5896+1256= $$

FAQ

Everything you need to know about this question

Why do I subtract 1000 from both sides?

When you have $1000 + \Box = 1001$ , subtracting 1000 from both sides keeps the equation balanced. The left side becomes just $\Box$ , and the right side becomes $1001 - 1000 = 1$ .

How is this different from regular subtraction problems?

In regular subtraction like $1001 - 1000$ , you already know both numbers. Here, you're working backwards from an addition fact to find the missing piece!

What if the missing number was bigger?

The method stays the same! For example, in $500 + \Box = 1001$ , you'd calculate $\Box = 1001 - 500 = 501$ . Always subtract the known addend from the sum.

Can I check my answer a different way?

Yes! You can also think about it as: "What do I add to 1000 to get 1001?" Since 1000 and 1001 are consecutive numbers, the difference is always 1.

Why are the other answer choices wrong?

10: 1000 + 10 = 1010 (too big)
100: 1000 + 100 = 1100 (way too big)
1000: 1000 + 1000 = 2000 (much too big)

Only 1 gives us exactly 1001!

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