Estimate differences

Key notes:

✨ Key Points

• Estimation means finding an answer that is close to the exact answer, but easier and quicker.
• Estimating differences means finding about how much two numbers differ by rounding them before subtracting.
• We usually round numbers to the nearest tens, hundreds, or thousands depending on the size of the numbers.
• Estimation helps us check if our actual subtraction answer is reasonable.

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🔹 Steps to Estimate Differences

• Look at the numbers you want to subtract.
• Round each number to the nearest 10, 100, or 1000 (as required).
• Subtract the rounded numbers.
• Write the estimated difference.

📝 Examples

Example 1:

Find the estimated difference of 387 – 242.

• Round 387 → 400
• Round 242 → 200
• Subtract: 400 – 200 = 200
  ✅ Estimated Difference = 200

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Example 2:

Find the estimated difference of 735 – 468.

• Round 735 → 700
• Round 468 → 500
• Subtract: 700 – 500 = 200
  ✅ Estimated Difference = 200

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Example 3:

Find the estimated difference of 5,642 – 2,389.

• Round 5,642 → 6,000
• Round 2,389 → 2,000
• Subtract: 6,000 – 2,000 = 4,000
  ✅ Estimated Difference = 4,000

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🌟 Remember

• Estimation gives an approximate answer, not the exact one.
• Always check whether you need to round to the nearest 10, 100, or 1000.
• Use estimation to save time and to check accuracy of exact subtraction.

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🏠 Practice Problems

Estimate the differences:

• 467 – 189
• 1,245 – 876
• 9,835 – 6,249
• 6,721 – 3,188
• 752 – 398

Learn with an example

Let’s practice!