Year 8 - Maths
Problem solving with estimation and rounding
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 use your knowledge of estimation and rounding to solve problems.
Key Notes
- It may be helpful to estimate an answer to check the magnitude is correct.
- It can be useful to use rounding to significant figures when dealing with very big or very small numbers in context.
- Estimates can help when making decisions about maximum or minimum possible answers in real life contexts.
- You can use Fermi estimation to find approximate solutions to problems.
Vocabulary To Learn
- Estimate: A quick estimate for a calculation is obtained from using approximate values, often rounded to 1 significant figure.
Common Mistakes To Avoid
- Using the wrong limits when dividing or subtracting in order to find the upper limit of a calculation or lower limit of a calculation.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
It may be helpful to estimate an answer to check the magnitude is correct. It can be useful to use rounding to significant figures when dealing with very big or very small numbers in context.
2. Use this key word in a maths sentence and explain it clearly. 'Estimate'
A quick estimate for a calculation is obtained from using approximate values, often rounded to 1 significant figure. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Using the wrong limits when dividing or subtracting in order to find the upper limit of a calculation or lower limit of a calculation. Correction: Drawing a number line to show with subtraction will help students see how to achieve an upper or lower limits of an error interval calculation. When using division, reiterating the division of number is the same as multiplying by its reciprocal.
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
- 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.