Free Grade 3 Working with Prime Numbers Flashcards
Free Grade 3 flashcards for Working with Prime Numbers: 12 real questions with a full answer key and worked solutions. Factors divide a number exactly; multiples are in its times table. The HCF is the biggest shared factor, the LCM the smallest shared multiple.
Free
Stretch
30 min
24
Learning objectives
Every objective is checkable, and each one maps to an activity and an assessment.
- RememberIdentify working with prime numbers
Identify working with prime numbers accurately in a familiar context.
Assessed by: Exit ticket of four short items
- UnderstandExplain working with prime numbers
Explain working with prime numbers accurately in a familiar context.
Assessed by: Exit ticket of four short items
- ApplyCalculate working with prime numbers
Calculate working with prime numbers accurately in a familiar context.
Assessed by: Exit ticket of four short items
- AnalyseCompare working with prime numbers
Compare working with prime numbers accurately in a familiar context.
Assessed by: Exit ticket of four short items
Prerequisites
Close these gaps first — each has its own free lesson, worksheet and quiz.
How Working with Prime Numbers works
Factors divide a number exactly; multiples are in its times table. The HCF is the biggest shared factor, the LCM the smallest shared multiple.
12 practice questions
Easy to hard, 24 marks in total. Try them first, then open the answers.
- 1.List all the factors of 18.[1]
- 2.List all the factors of 24.[1]
- 3.List all the factors of 12.[1]
- 4.List all the factors of 36.[1]
- 5.Find the highest common factor (HCF) of 8 and 12.[2]
- 6.Find the highest common factor (HCF) of 42 and 30.[2]
- 7.Find the highest common factor (HCF) of 4 and 6.[2]
- 8.Find the highest common factor (HCF) of 10 and 10.[2]
- 9.Find the lowest common multiple (LCM) of 32 and 24.[3]
- 10.Find the lowest common multiple (LCM) of 18 and 27.[3]
- 11.Find the lowest common multiple (LCM) of 10 and 15.[3]
- 12.Find the lowest common multiple (LCM) of 24 and 16.[3]
Show answers and working
1. 1, 2, 3, 6, 9, 18
Find factor pairs that multiply to 18. 1 × 18 2 × 9 3 × 6
2. 1, 2, 3, 4, 6, 8, 12, 24
Find factor pairs that multiply to 24. 1 × 24 2 × 12 3 × 8 4 × 6
3. 1, 2, 3, 4, 6, 12
Find factor pairs that multiply to 12. 1 × 12 2 × 6 3 × 4
4. 1, 2, 3, 4, 6, 9, 12, 18, 36
Find factor pairs that multiply to 36. 1 × 36 2 × 18 3 × 12 4 × 9 6 × 6
5. 4
List factors of 8 and 12. The largest factor they share is 4.
6. 6
List factors of 42 and 30. The largest factor they share is 6.
7. 2
List factors of 4 and 6. The largest factor they share is 2.
8. 10
List factors of 10 and 10. The largest factor they share is 10.
9. 96
HCF(32, 24) = 8. LCM = 32 × 24 ÷ 8 = 96.
10. 54
HCF(18, 27) = 9. LCM = 18 × 27 ÷ 9 = 54.
11. 30
HCF(10, 15) = 5. LCM = 10 × 15 ÷ 5 = 30.
12. 48
HCF(24, 16) = 8. LCM = 24 × 16 ÷ 8 = 48.
Worked examples
List all the factors of 40.
- Find factor pairs that multiply to 40.
- 1 × 40
- 2 × 20
- 4 × 10
- 5 × 8
- Answer: 1, 2, 4, 5, 8, 10, 20, 40
Find the highest common factor (HCF) of 8 and 4.
- List factors of 8 and 4.
- The largest factor they share is 4.
- Answer: 4
Find the lowest common multiple (LCM) of 20 and 30.
- HCF(20, 30) = 10.
- LCM = 20 × 30 ÷ 10 = 60.
- Answer: 60
Interactive practice
Free, no account required — answer on screen or print it.
Common mistakes
What learners typically get wrong, and how to fix it.
Mixes up factors and multiples.
Correction: Factors are Few (they fit inside), multiples are Many (they go on forever).
Misses factor pairs.
Correction: Work through 1, 2, 3… in order until the pairs meet.
Teacher tips
- · Use factor rainbows to show pairs.
Parent tips
- · Ask how many ways 24 sweets can be put into equal bags.
Real-life applications
- · Arranging chairs in equal rows, syncing bus timetables (LCM).
Assessment objectives
How mastery is evidenced, and which standards it maps to.
Every free resource for Working with Prime Numbers
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Frequently asked
- Is this Grade 3 Working with Prime Numbers flashcards really free?
- Yes. Every flashcards on FreeMathWorksheet is free to use, print and share — no account, no paywall and no watermark.
- What should a learner already know before this?
- Start with Introducing Prime Numbers, Multiples. Each one has its own free lesson, worksheet and quiz.
- How is the flashcards sequenced?
- Recognition first, then understanding, application, reasoning and finally mastery — the same ladder used across every free resource on the platform.
- What comes next after Working with Prime Numbers?
- Move on to Prime Numbers in Context, Factors, Multiples, Prime Factorisation, which build directly on this idea.
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