NotesMath · P5 / P6Percentage
Percentage Quick Notes
Percentage is a fraction with denominator 100. Convert freely between decimals, fractions and percentages.
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1
Convert
0.25 = 25% = 1/4. 0.5 = 50% = 1/2.
2
Percentage of a Number
'20% of 80' means 20/100 × 80 = 16.
3
Percentage Change
(New − Old) / Old × 100%. Positive = increase, negative = decrease.
4
Discount & Interest
Final price = Original × (100 − discount%) / 100.
⚠️ Common Mistakes
Don't fall into these traps
- ✕Using the new value instead of old as the base
- ✕Confusing % of vs % increase
- ✕Adding percentages that share different bases
Teacher Hidayah's Tip
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Write '100 units = original' at the top of the page. Everything follows.
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Sample Question
Try it, then read the worked solution
Question
A $60 shirt is discounted by 25%. Final price?
Worked Solution
- 1Discount = 25/100 × 60 = $15
- 2Final = 60 − 15 = $45
Everything for Percentage
Each topic in the library comes with the full 5-piece bundle.
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Before-Class Prep
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After-Class Practice
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Downloadable Notes
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One-Page Mind Map
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Mistake Fix Zone