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Factors of 18 are 3,3,& 2.
Factors of 21 are 3 & 7
One lot of '3' is common to both so '3' is the HCF.
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Earn +20 ptsQ: What is the highest common factor of 18 and 21?
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Which number goes into 21 and 18?
The highest common factor of 21 and 18 is 3
What is the highest common factor of 28 and 21?
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What is the highest common factor of 21 and 105?
Since 21 is a factor of 105, it is automatically the GCF.
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The GCF is 1.
What are the GCF 63 and 84?
63 and 84's highest common factor is 21.
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