Percentage Reference Card
Free printable poster for classrooms and revision
Percentage Reference Card
percentages.co.uk
The word 'percentage' comes from the Latin 'per centum', meaning by the hundred. The % symbol evolved from the Italian 'per cento', where the letters were gradually contracted into the two circles and line we use today.
Key Equivalents
| Percentage | Decimal | Fraction |
|---|---|---|
| 1% | 0.01 | 1/100 |
| 5% | 0.05 | 1/20 |
| 10% | 0.1 | 1/10 |
| 20% | 0.2 | 1/5 |
| 25% | 0.25 | 1/4 |
| 50% | 0.5 | 1/2 |
| 75% | 0.75 | 3/4 |
| 100% | 1 | 1 |
Key Formulas
Percentage of a number
Result = (P ÷ 100) × Number
Percentage increase
Result = Original × (1 + P/100)
Percentage decrease
Result = Original × (1 - P/100)
Reverse percentage
Original = Amount ÷ (1 ± P/100)
Percentage change
Change% = ((New - Old) ÷ Old) × 100
Percentage difference
Diff% = (|A - B| ÷ ((A+B)/2)) × 100
Mental Maths Tips
- Find 10%: divide by 10
- Find 5%: halve the 10% value
- Find 1%: divide by 100
- Find 20%: double the 10% value
- Find 50%: halve the number
- Find 25%: halve, then halve again
100 Squares Grid
Each shaded column = 10%
Free resource from percentages.co.uk | No sign-up required
Free to print and use in your classroom or for personal revision. Please credit percentages.co.uk.