Estimate sums and differences of decimals

key notes :

1. Understanding Estimation

• Estimation is a quick way to find an approximate answer.
• It helps in checking if the actual calculation is reasonable.

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2. Rounding Decimals for Estimation

• Round decimals to the nearest whole number or the nearest tenth.
• Example:
  • 3.68 → 4 (rounded to the nearest whole number)
  • 3.68 → 3.7 (rounded to the nearest tenth)

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3. Estimating Sums of Decimals

• Round each decimal number.
• Add the rounded numbers.
• Example:
  • 4.72+3.29
  • Round: 4.72≈5,3.29≈3
  • Estimate: 5+3=8

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4. Estimating Differences of Decimals

• Round each decimal number.
• Subtract the rounded numbers.
• Example:
  • 9.56−2.41
  • Round: 9.56≈10,2.41≈2
  • Estimate: 10−2=8

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5. Using Front-End Estimation

• Focus on the first digit and adjust the rest.
• Example:
  • 7.83+6.45
  • Front-end estimation: 7+6=13

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6. Compatible Numbers for Estimation

• Choose numbers that are easy to add or subtract mentally.
• Example:
  • 5.89+2.14≈6+2=8

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7. Importance of Estimation in Real Life

• Helps in budgeting and shopping.
• Useful in measuring distances and time calculations.

Learn with an example

Let’s practice!