Percentages Basics
Year 7 🔢 Number Find percentages of amounts, percentage increase and decrease.
📊 What is a Percentage?
A percentage is a number out of 100. The symbol % means "per hundred".
⚡ Key Formula
$$\text{Percentage} = \frac{\text{part}}{\text{whole}} \times 100$$Example: 18 out of 25 as a percentage: $\frac{18}{25} \times 100 = 72\%$
🔄 Converting Between Fractions, Decimals & Percentages
These three forms all represent the same value — learn to switch between them fluently.
| Fraction | Decimal | Percentage |
|---|---|---|
| $\frac{1}{2}$ | 0.5 | 50% |
| $\frac{1}{4}$ | 0.25 | 25% |
| $\frac{3}{5}$ | 0.6 | 60% |
| $\frac{1}{8}$ | 0.125 | 12.5% |
💰 Finding a Percentage of an Amount
To find a percentage of a quantity, convert the percentage to a decimal and multiply.
- Write the percentage as a decimal (divide by 100).
- Multiply by the amount.
Example: Find 35% of £240 → $0.35 \times 240 = £84$
To find 10%, divide by 10. Build other percentages from there: 15% = 10% + 5%.
Ready to test yourself? Click the Quiz tab above to answer questions on this topic!
Interactive Demonstration — Percentages Basics
📊 Percentage Calculator