Year 8 - Maths
Checking by estimating
Estimation and rounding
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit helps pupils understand rounding to different decimal places, and significant figures. Pupils will also learn how to truncate numbers and understand the contexts in which these skills are useful. The unit ends will an exploration of rounding and inequality errors.
Lesson Summary
You will learn to estimate and check if solutions to problems are of the correct magnitude.
Key Notes
- Estimation should give you an idea of the size of an answer.
- It is useful to estimate the answer to calculations so you can check your answers make sense.
- Errors in calculations can be found by using estimates.
Vocabulary To Learn
- Significant figures: Significant figures are the digits in a number that contribute to the accuracy of the number.
- Estimate: A quick estimate for a calculation is obtained from using approximate values, often rounded to 1 significant figure.
Common Mistakes To Avoid
- When rounding a number, pupils write the first significant digit(s). e.g 36 789 is 4.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Estimation should give you an idea of the size of an answer. It is useful to estimate the answer to calculations so you can check your answers make sense.
2. Use this key word in a maths sentence and explain it clearly. 'Significant figures'
Significant figures are the digits in a number that contribute to the accuracy of the number. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When rounding a number, pupils write the first significant digit(s). e.g 36 789 is 4. Correction: The use of the place value table shows the magnitude of the number, thus preserving their place value.
More Lessons In This Unit
- Checking understanding of rounding Study Guide
- Degrees of accuracy Study Guide
- Estimating numerical calculations Study Guide
- Inequality notation to express error Study Guide
- Overestimating vs underestimating Study Guide
- Problem solving with estimation and rounding Study Guide
- Rounding decimals to significant figures Study Guide
- Rounding errors Study Guide
- Rounding integers to one significant figure Study Guide
- Rounding integers to significant figures Study Guide
- Rounding to any number of decimal places Study Guide
- Rounding to three decimal places Study Guide
- Securing understanding of rounding Study Guide
- Truncating Study Guide
- Using inequality notation for errors in calculations Study Guide
Browse all guides in the Year 8 Maths guide library.