Highest common factor (HCF)
Find the highest common factor of two numbers: the biggest number that divides into both. Each number is built from three small primes, so factor trees work well.
The step-by-step working shows how the common factor is found.
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What changes each time
- Numbers built from the primes 2, 3, 5 and 7
- Numbers from 8 to 343
- A new pair every time
More multiplication and division practice
- Multiplication as equal groups (Grade 2)
- Division by sharing and grouping (Grade 2)
- Arrays (equal rows) (Grade 2)
- Multiplying whole numbers (Grade 3)
- Short division (Grade 3)
- Matching multiplication sentences to pictures (Grade 3)
- Fact family triangles (Grade 3)
- Times table grid (Grade 3)
- Area model multiplication (Grade 3)
- Multiplying by multiples of ten (Grade 3)
- Lowest common multiple (LCM) (Grade 3)
- Missing digits in long multiplication (Grade 4)