# What is the greatest common factor of 42, 63, and 105?

is 21

Factors of 42 are {1,2,3,6,7,14,21,42}

Factors of 63 are {1,3,7,9,21,63}

Factors of 105 are {1,3,5,7,15,21,35,105}

Common factors are just {1,3,7,21} and

Greatest Common Factor is 21.

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