About this worksheet

This free Year 8 percentage increase and decrease worksheet is written for the Western Australian curriculum and mapped to SCSA content description WA8MNAC1. It targets one skill so students can practise until it sticks: by the end, students can say “I can increase and decrease amounts by a percentage using decimal multipliers, including GST, discounts and mark-ups.”

What’s inside

• Key idea box – a short explanation with worked examples to read before starting.
• A · Fluency (16 questions) – quick practice to build accuracy.
• B · Core (10 questions) – worded problems set in everyday Australian contexts.
• C · Reasoning (4 questions) – explain, justify and spot the error.
• D · Challenge (4 questions) – harder multi-step and problem-solving questions for students ready to stretch.
• Separate marking key – every answer with working, plus mark allocations and marking criteria for reasoning questions.

Skills covered

• Using decimal multipliers such as 1.1 and 0.85
• Calculating GST, discounts and mark-ups
• Applying successive percentage changes

How to use this worksheet

Start with the Key idea box, then complete Section A (use a calculator only where a question says so). Most students should attempt Sections B and C; Section D suits students aiming for the top of the class or preparing for accelerated or extension maths. The worksheet is marked out of 58, and the score box on the last page helps students see which section needs more practice.

Common mistakes to watch for

• Adding successive discounts, e.g. 25% then 10% as 35%
• Using 0.15 instead of 0.85 for 15% off
• Finding the change but not the new amount
• Confusing a 150% mark-up with a price of 150%

Where this fits in the WA Year 8 sequence

Percentage Increase and Decrease sits in the Calculating with number sub-strand of Number and algebra. It is one of a set of short, single-skill EduLift worksheets that split each Year 8 content description into sub-skills. Use the previous and next links to work through the sequence in order.

Common errors we see in tutoring

• Adding successive discounts, e.g. 25% then 10% as 35%
• Using 0.15 instead of 0.85 for 15% off
• Finding the change but not the new amount
• Confusing a 150% mark-up with a price of 150%