Three names for one amount
A bus ticket says three quarters. You can also write 0.75 or 75%. In the lab, slide the mark to the amount. The fraction, decimal and percentage move together.
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Step 1 of 4
- 3/4 marked on a 0-to-100 scale.
- Divide: 3 ÷ 4 = 0.75.
- Multiply by a hundred: 75%.
- One mark, three names.
The rule
A fraction, a decimal and a percentage can name one amount.
- Divide the top number by the bottom number for the decimal.
- Multiply the decimal by 100 for the percentage.
- To change a percentage back to a fraction, write it over 100. Then divide the top and bottom by their highest common factor. That is the biggest number that divides both.
Because per cent counts hundredths, 0.75 becomes 75%.
Examples:
- 3/5: 3 ÷ 5 = 0.6. Then 0.6 × 100 = 60, so 60%.
- 1/8: 1 ÷ 8 = 0.125. Then 0.125 × 100 = 12.5, so 12.5%.
- 60%: 60/100. Divide top and bottom by 20 to get 3/5.
A percentage need not be a whole number.
| Percentage | Fraction | Decimal |
|---|---|---|
| 50% | 1/2 | 0.5 |
| 25% | 1/4 | 0.25 |
| 10% | 1/10 | 0.1 |
| 1% | 1/100 | 0.01 |
Watch out!
1/5 is not 0.5. Divide: 1 ÷ 5 = 0.2. So 1/5 is 20%. The 0.5 is the decimal for 1/2.