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What is the GCF of 21 and 63?

1 Answer

sente · Skittles

Oct 23, 2016

$21$ $21$

Explanation:

The GCF (greatest common factor) of two numbers is the greatest number which is a factor of both of them.

The factors of $21$ $21$ are: $1, 3, 7, 21$ $1, 3, 7, 21$

The factors of $63$ $63$ are: $1, 3, 7, 9, 21, 63$ $1, 3, 7, 9, 21, 63$

The greatest number which is on both lists is $21$ $21$ , meaning $21$ $21$ is the greatest common factor.

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