Learn the 3-Step Method
1Write it as a fraction.
Score over total: 18 out of 20 → 18/20.
2Make the denominator 100.
Multiply top and bottom by the same number: ×5 here.
3Read off the percentage.
90 out of 100 = 90%.
Worked Example
A netball team wins 13 of its 25 matches. What percentage did it win?
Watch Out! Common Mistakes
Wrong! The bottom is the total possible (20), not 100. 18/20 = 90%.
Wrong! Multiply top AND bottom by 5: 18/20 = 90/100 = 90%.
Impossible! You can’t score more than everything. 13/25 = 52%.
⬇ Cheat Sheet
- Write score over total as a fraction.
- Multiply top and bottom to make the bottom 100.
- Read the top number as the %.
- Totals that divide into 100: 10 (×10), 20 (×5), 25 (×4), 50 (×2).
📖 Continue Your Journey
Quick summary
- Write it as a fraction first: 18 out of 20 = 18/20.
- Scale the denominator to 100: ×5 gives 90/100.
- Read off the percentage: 90%.
- The bottom number is the total possible, never automatically 100.
Frequently asked questions
How do you write a test score as a percentage?
Put the score over the total, then scale the fraction to hundredths: 18/20 = 90/100 = 90%.
What if the total doesn't divide into 100?
Divide instead: score ÷ total × 100. For 15 out of 40, 15 ÷ 40 = 0.375 = 37.5%. At KS2, questions almost always use friendly totals like 10, 20, 25 and 50.
Why is this a key 11+ skill?
Score-to-percentage questions appear constantly, and the same scaling idea underpins pie charts, probability and data work.
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