Maths Library

Percentage Increase and Decrease: Year 10 maths

This topic covers increasing and decreasing quantities by a given percentage, as well as calculating percentage change. Students practise using additive steps and single-step multiplier methods.

Open in full editor

What this covers

Percentage Increase and Decrease is taught in Year 10 (age 15 to 16) as a topic to introduce. It sits in the Percentages strand.

Worked example

Increase 80 by 15%

  1. Find 10%: 8010 = 8
  2. Find 5%: 82 = 4
  3. Total increase: 8 + 4 = 12
  4. Add to original: 80 + 12 = 92

Answer: 92

Difficulty scale

The sheet generator offers five difficulty settings for this topic.

  1. Integer increases/decreases using 10%, 20%, or 50% on simple numbers
  2. Increases/decreases using multiples of 5% on 2-digit or 3-digit values
  3. Any integer percentage increase/decrease using multiplier methods
  4. Calculating percentage change given original and new values
  5. Reverse percentage problems or multi-step word problems involving compound change

Common mistakes

  • Subtracting or adding the percentage value directly (e.g. 50 + 10% = 60.1)
  • In reverse problems, calculating percentage of the final amount instead of the original

Curriculum links

Indicative matches to Australian Curriculum v9. Check wording and codes against the official document.

  • AC9M10N03 Solve practical problems involving compound interest, rates, and repeated percentage change.

Sample sheet and answers

Six questions at the level's usual difficulty. Open the editor to change, add or regenerate any of them.

Percentage Increase and Decrease

Year 10 maths

Qs
6
Marks
24
NameDateScore / 24
1.
A coat costs $160.00. In a sale the price rises by 10%. Find the new price.
[4]
2.
A coat costs $260.00. In a sale the price falls by 30%. Find the new price.
[4]
3.
A coat costs $360.00. In a sale the price rises by 20%. Find the new price.
[4]
4.
A coat costs $400.00. In a sale the price falls by 10%. Find the new price.
[4]
5.
A coat costs $60.00. In a sale the price rises by 10%. Find the new price.
[4]
6.
A coat costs $100.00. In a sale the price rises by 30%. Find the new price.
[4]

Answer key

  1. $176.00The multiplier is 1.1; $160.00 × 1.1 = $176.00
  2. $182.00The multiplier is 0.7; $260.00 × 0.7 = $182.00
  3. $432.00The multiplier is 1.2; $360.00 × 1.2 = $432.00
  4. $360.00The multiplier is 0.9; $400.00 × 0.9 = $360.00
  5. $66.00The multiplier is 1.1; $60.00 × 1.1 = $66.00
  6. $130.00The multiplier is 1.3; $100.00 × 1.3 = $130.00