What is the GCF of 30 and 42?

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Answer 1 · 2016-04-27T03:09:04

Factors of #30# are #{1,2,3,5,6,10,15,30}#.

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

Common factors are #{1,2,3,6}#.

Greatest Common Factor is #6#.

Answer 2 · 2016-08-19T21:21:37

# GCF = 2xx3 = 6#

It is possible to find the GCF by writing each number as the product of its prime factors. This shows which prime factors are shared by both numbers.

#" "30 = 2xx3xx5#
#" "42 = 2xx3 xxcolor(white)(5x)7#

#GCF = " "2xx3" " = 6#

This method is particularly useful with big numbers or when working with several numbers.