❌ Wrong: Adding to ratios: 2:3 + 1:2 = 3:5
✅ Right: Cannot add ratios directly
Convert to fractions or find common format first
❌ Wrong: Ignoring order: 3:5 same as 5:3
✅ Right: Order matters in ratios
3:5 means first is 3 parts, second is 5 parts
❌ Wrong: Not converting units: 2m : 50cm = 2:50
✅ Right: 200cm : 50cm = 4:1
Always convert to same units before simplifying
❌ Wrong: Forgetting to simplify: Answer 10:15
✅ Right: 10:15 = 2:3
Always give ratio in simplest form
This exam tips covers Common Mistakes to Avoid within Ratio Basics for GCSE Mathematics. Revise Ratio Basics in Number for GCSE Mathematics with 12 exam-style questions and 22 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 13 of 15 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Practice questions for Ratio Basics
Write the ratio 12:18 in its simplest form.
Explain the difference between the ratio 3:5 and the ratio 5:3.
Quick recall flashcards
Order in Ratios
Order MATTERS!
Boys:Girls = 3:5 means:
• 3 boys for every 5 girls
Girls:Boys = 5:3 means:
• 5 girls for every 3 boys
Different meanings!
What is a ratio?
A comparison of quantities of the same kind
Written as a:b or a/b
Example: 3:5 means '3 parts to 5 parts'