Year 8 - Maths
Rounding errors
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 appreciate the impact of rounding errors when using a calculator (or other technology), and the way that these can be compounded to result in large inaccuracies.
Key Notes
- When given a rounded number you can say what the biggest and smallest values of the unrounded number could have been.
- When using technology for multi-step calculations you might round along the way.
- Rounding too early can cause answers to be incorrect
- Repeated rounding in multi-step calculations can lead to large errors.
Vocabulary To Learn
- Significant figures: Significant figures are the digits in a number that contribute to the accuracy of the number
Common Mistakes To Avoid
- Rounding prematurely during multi-step calculations.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
When given a rounded number you can say what the biggest and smallest values of the unrounded number could have been. When using technology for multi-step calculations you might round along the way.
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: Rounding prematurely during multi-step calculations. Correction: Encourage to use of fractions (where possible) or the use of the ANS button.
More Lessons In This Unit
- Checking by estimating Study Guide
- 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 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.