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Auralith Learning

Year 8 · Maths · Percentages · Lesson 2

Percentage increase and decrease

Increase and decrease amounts by a percentage, using both the build-up method and decimal multipliers, including real-life problems.

Whiteboard video lesson: Percentage increase and decrease

26-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Increase an amount by a percentage
  • Decrease an amount by a percentage
  • Find the multiplier for a percentage change
  • Use multipliers with a calculator
  • Solve problems like sales, VAT and pay rises

The method

  1. Increase by p%: 100% + p%.
  2. Decrease by p%: 100% − p%.
  3. Divide by 100 to get the multiplier.
  4. Multiply the amount by the multiplier.

Key words: increase, decrease, multiplier, VAT, discount.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

Increase £40 by 10%.

  1. Step 1: 10% = £40 ÷ 10 = £4
  2. Step 2: £40 + £4 = £44

Answer: £44

Question 2

Decrease £18 by 50%.

  1. Step 1: 50% = half: £18 ÷ 2 = £9
  2. Step 2: £18 − £9 = £9

Answer: £9

Question 3

Increase £120 by 25%.

  1. Step 1: 25% = a quarter: £120 ÷ 4 = £30
  2. Step 2: £120 + £30 = £150

Answer: £150