Recognise composite numbers
- List factor pairs.
- Check whether there are more than two factors.
- If yes, the number is composite.
Answer: 15 is composite because 1, 3, 5 and 15 divide it
🔢 Number
Composite numbers
Learn composite numbers with a GCSE-style explanation, help guide, worked example, practice question and flashcards.
Global XP
Level 10 / 100 XP
1. Explanation
Key idea
- Composite numbers is part of number and appears often in KS3–GCSE maths.
- Composite numbers are whole numbers with more than two factors.
- Use the worked model, help guide, interactive question and flashcards to practise composite numbers until the steps feel automatic.
Real-life examples
- Shopping, sport, travel, science, design and everyday decisions all use this skill.
2. Visual
Composite numbers learning map
Understand the key idea → follow the help guide → practise a question → check your method → build speed with flashcards.
3. Help guide
How to tackle Composite numbers
- Learn the rule: Composite numbers are whole numbers with more than two factors.
- Worked model: List factor pairs. Check whether there are more than two factors. If yes, the number is composite.
- Try the interactive question without looking at the answer first.
- Use the flashcards to test the rule, the method and a common check.
4. Worked examples
Step-by-step working
5. Interactive questions
Try it yourself
Is 21 composite?
6. Flashcards
Master quick recall
Flip each card, then choose whether you know it or need more practice.
0 mastered
FrontRule for Composite numbers
BackComposite numbers are whole numbers with more than two factors.
FrontExample answer: Is 21 composite?
Back21 has factors 1, 3, 7 and 21, so it is composite.
FrontCommon check for Composite numbers
BackCheck units/notation, compare with an estimate, and make sure the answer matches the question.
7. Finish
Complete this topic
When you have read the examples, tried the question and reviewed flashcards, claim your topic completion XP.