Year 8 - Maths
Truncating
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 a value by truncating to a given degree of accuracy.
Key Notes
- When estimating ages, it is convention to use truncation.
- Truncation can be used to estimate any integer to a given accuracy.
- Truncation can be used to estimate any number to a given accuracy.
Vocabulary To Learn
- Truncate: Truncation is the simplifying a number by 'cutting off' one or more of the digits and replacing them with zeros if necessary to preserve place value.
- A degree of accuracy: A degree of accuracy shows how precise a number or measurement is.
Common Mistakes To Avoid
- When truncating, pupils are tempted to round. Also, when truncating, they cut off the number without thinking about the magnitude.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
When estimating ages, it is convention to use truncation. Truncation can be used to estimate any integer to a given accuracy.
2. Use this key word in a maths sentence and explain it clearly. 'Truncate'
Truncation is the simplifying a number by 'cutting off' one or more of the digits and replacing them with zeros if necessary to preserve place value. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When truncating, pupils are tempted to round. Also, when truncating, they cut off the number without thinking about the magnitude. Correction: The use of the place value table shows the magnitude of the number, thus preserving their place value when truncating.
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 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
- Using inequality notation for errors in calculations Study Guide
Browse all guides in the Year 8 Maths guide library.