Greatest common factor (GCF)
Greatest common factor (GCF)
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Work out the GCF (greatest common factor) of two numbers.
What is the greatest common factor of 12 and 18?
This exercise finds the greatest common factor (GCF) of two numbers — the largest number that divides both of them exactly. You will use the GCF later for simplifying fractions and for problems that involve common groupings.
What does this generator do?
Picks two numbers from a friendly range (4 to 48) so the GCF is reasonable to do mentally.
How to use it
Write the prime factorisation of both numbers and multiply the factors they share. Or keep dividing both numbers by the same number until you run out of common factors.
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