Year 10 - Maths
Checking and securing understanding of percentage decrease
Percentages
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will learn how to perform simple and compound interest calculations using percentages.
Lesson Summary
You will learn to decrease an amount by a given percentage.
Key Notes
- In all of these representations a single multiplier can be used to find a percentage decrease.
- Representation can help when you are not using a calculator.
- A multiplier is significantly faster when using a calculator.
- To decrease you are going below the original amount.
Vocabulary To Learn
- Proportion: If two things are proportional then the ratio of part to whole is maintained and the multiplicative relationship between parts is also maintained.
Common Mistakes To Avoid
- When using multipliers, pupils can mistake a decimal for the percentage decrease. e.g. 0.52 is a 52% decrease, rather than recognising a 48% decrease
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
In all of these representations a single multiplier can be used to find a percentage decrease. Representation can help when you are not using a calculator.
2. Use this key word in a maths sentence and explain it clearly. 'Proportion'
If two things are proportional then the ratio of part to whole is maintained and the multiplicative relationship between parts is also maintained. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When using multipliers, pupils can mistake a decimal for the percentage decrease. e.g. 0.52 is a 52% decrease, rather than recognising a 48% decrease. Correction: Reminding students that a decimal multiplier greater than 1 means an increase, and a decimal multiplier less than 1 means a decrease. The latter requires a subtraction from 1 or 100%.
More Lessons In This Unit
- Advanced problem solving with percentages Study Guide
- Calculating compound interest rates Study Guide
- Changing compound interest rates Study Guide
- Checking and securing understanding of finding a percentage Study Guide
- Checking and securing understanding of percentage increase Study Guide
- Compound interest calculations Study Guide
- Compound interest calculations with technology Study Guide
- Percentage profit and loss Study Guide
- Problem solving with percentages Study Guide
- Simple and compound interest Study Guide
- Simple interest calculations Study Guide
- Simple interest calculations with technology Study Guide
Browse all guides in the Year 10 Maths guide library.