KS2 Percentage Revision Notes
KS2 Percentage Revision Notes
Year 5 and Year 6 | percentages.co.uk
1. What is a percentage?
The word per cent comes from Latin and means "per hundred". So whenever you see the % symbol, it means "out of 100".
- 50% means 50 out of every 100
- 25% means 25 out of every 100
- 100% means the whole thing (all 100 out of 100)
- 1% means just 1 out of every 100
The 100-square analogy
Imagine a grid of 100 small squares. If 25 squares are shaded, that is 25%. If 50 squares are shaded, that is 50%. If all 100 squares are shaded, that is 100%. Because percentages are always "out of 100", the grid of 100 squares is a perfect way to picture them.
2. Key percentages to know
Learn these equivalents by heart. They come up in almost every percentage question.
| Percentage | Meaning | Fraction | Decimal |
|---|---|---|---|
| 100% | The whole amount | 1 whole | 1.0 |
| 50% | Half | 1/2 | 0.5 |
| 25% | One quarter | 1/4 | 0.25 |
| 75% | Three quarters | 3/4 | 0.75 |
| 10% | One tenth | 1/10 | 0.1 |
| 20% | One fifth | 1/5 | 0.2 |
| 1% | One hundredth | 1/100 | 0.01 |
3. Finding a percentage of an amount
The easiest method at KS2 is the 10% method. Find 10% first by dividing by 10, then use that to work out other percentages.
Step-by-step method
- Find 10% first: divide the amount by 10.
- Use that result to find other percentages by multiplying or dividing.
Worked examples using 80 as the amount:
Find 10% of 80
80 ÷ 10 = 8
Find 20% of 80
10% = 8, so 20% = 8 × 2 = 16
Find 5% of 80
10% = 8, so 5% = 8 ÷ 2 = 4
Find 25% of 80
25% = one quarter, so 80 ÷ 4 = 20
Find 50% of 80
50% = half, so 80 ÷ 2 = 40
4. Expressing a number as a percentage
To write one number as a percentage of another, use this formula:
(part ÷ whole) × 100
Worked example
A pupil scores 15 out of 60 in a test. What is their percentage score?
Step 1: Divide the part by the whole: 15 ÷ 60 = 0.25
Step 2: Multiply by 100: 0.25 × 100 = 25%
The pupil scored 25%.
5. Practice questions
Try these questions without looking at the answers first. Then use the button below to check your work.
- Find 10% of 150.
- Find 25% of 200.
- Find 20% of 65.
- Find 5% of 120.
- Write 12 as a percentage of 48.
- A bag of 40 sweets contains 10 red sweets. What percentage are red?