Year 8 - Maths
Rounding decimals to significant figures
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 round decimals to a required number of significant figures.
Key Notes
- Numbers bigger than 1 with decimals places can be rounded to significant figures.
- When working with numbers smaller than one it is important to carefully identify the first significant figure.
- Once the first significant figure is identified you can find any significant figure.
- It is important to know when zeros are and are not significant.
Vocabulary To Learn
- Significant figure: Significant figures are the digits in a number that contribute to the accuracy of the number. The first significant figure is the first non-zero digit.
- Round: To change a number into another number that is approximately the same value but is easier to work with. E.g. round 561 to the nearest 10 is 560.
Common Mistakes To Avoid
- Assuming all zero digits are not significant.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Numbers bigger than 1 with decimals places can be rounded to significant figures. When working with numbers smaller than one it is important to carefully identify the first significant figure.
2. Use this key word in a maths sentence and explain it clearly. 'Significant figure'
Significant figures are the digits in a number that contribute to the accuracy of the number. The first significant figure is the first non-zero digit. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Assuming all zero digits are not significant. Correction: Designing questions that contain zero digits in a variety of positions.
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 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.