Percentage Increase Made Simple (KS2)

P5Percentage Increase

Make it bigger by a percentage.

A percentage increase adds a percentage of the original on top.

A £40 game rises in price by 20%. What's the new price?

20% of £40 = £8

£40 + £8 = £48

original 100% + extra 20%

Increase = original + (percentage of original).

Learn the 3-Step Method

1Find the percentage of the original.

20% of £40: 10% is £4, so 20% is £8.

20% → £8

2Add it on.

New price = original + increase: 40 + 8 = 48.

40 + 8 = 48

3Sense-check.

An increase means the answer must be MORE than the original.

£48 > £40 ✓

💡 Key IdeaIncreasing by 20% means the new amount is 120% of the original — the whole plus a fifth more.

Worked Example

A gym has 60 members. Membership grows by 15%. How many members now?

10% and 5%

10% of 60 = 6
5% of 60 = 3

→

15%

6 + 3 = 9

→

Add on

60 + 9 = 69

→

✓ Answer

69 members

Watch Out! Common Mistakes

Forgetting to add the increase on.

£40 + 20% = £8 ✕

Wrong! £8 is just the increase. The new price is 40 + 8 = £48.

Adding the percentage as pounds.

£40 + 20% = 40 + 20 = £60 ✕

Wrong! 20% is a fraction of the original, not £20. 20% of £40 = £8, so £48.

Answer smaller than the original.

increase → £32 ✕

Check! An increase must give MORE than the original. £32 would be a decrease.

⬇ Cheat Sheet

PERCENTAGE INCREASE

Find the percentage of the original amount.
ADD it to the original.
Increase by 20% = 120% of the original.
Check: the answer must be bigger than you started with.

Example: £40 + 20% → 20% of £40 = £8 → £48

📖 Continue Your Journey

✓ P1 What Are Percentages?✓ P2 Percentages, Fractions and Decimals ✓ P3 Finding 50%, 25% and 10%✓ P4 Percentage of an Amount P5 Percentage Increase P6 Percentage Decrease P7 Percentages and Money P8 One Number as a Percentage of Another P9 Comparing with Percentages P10 Percentage Change P11 Reverse Percentages P12 Percentage Problem Solving

→

Next Lesson: P6 Percentage DecreaseMake it smaller by a percentage.

📄 Free printable: Download the Percentage Increase cheat sheet (PDF) — keep it by your child's desk.

Quick summary

Find the percentage of the original amount first.
Add it to the original: £40 increased by 20% is £40 + £8 = £48.
Increasing by 20% is the same as finding 120% of the original.
An increase must always give more than you started with.

Frequently asked questions

How do you increase an amount by a percentage?

Find that percentage of the original, then add it on. To increase £40 by 20%: 20% of £40 is £8, so the answer is £48.

What does 'increase by 100%' mean?

The amount doubles — you add the whole original on top. £30 increased by 100% is £60.

What's the most common mistake with percentage increase?

Stopping after finding the percentage (giving £8 instead of £48), or adding the percentage number as if it were pounds (£40 + £20). The two-step routine prevents both.

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P4 Percentage of an Amount

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P6 Percentage Decrease