The note
How schools teach it now
Children build percentages from easy ones: 10% (divide by 10), 50% (halve), 25% (quarter), 1% (divide by 100), then combine them, e.g. 35% = 10% + 10% + 10% + 5%. 'Per cent' means 'out of 100'.
5-minute kitchen-table activity
Spot a sale sign: 'This £60 coat has 20% off. How much do we save, and what does it cost now?' (10% is £6, so 20% is £12 and it costs £48.) Take turns inventing discounts.
Worked example
A £80 bike is reduced by 35%. What is the sale price?
- 10% of £80 = £8, so 30% = £24.
- 5% is half of 10% = £4.
- 35% = £24 + £4 = £28 off.
- £80 − £28 = £52.
Answer: £52
Common mistakes to watch for
- Giving the discount (£28) instead of the new price.
- Thinking 5% is a fifth (it's a twentieth).
- Dividing by 10 for every percentage.
Encouragement
- Try saying
- “Start with 10%. What can you build from it?”
- Rather than
- “Just use the formula.”