Key learning points

1. Common factors can be found by comparing the products of their primes.
2. The highest common factor of two numbers can be found by comparing the prime factorisation of both numbers.
3. Sometimes a Venn diagram can help identify the highest common factor of two numbers.
4. The highest common factor of more than two numbers can be found using prime factorisation.

Keywords

• Prime factorisation - a method to find the prime factors of a given integer

• Highest common factor - The highest common factor of two or more integers  which can be divided by all other possible common factors

• HCF - an abbreviation for highest common factor

Common misconception