![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
Method 1:
\List the factors of each number.
\Factors of 42: 2, 3, 6, 7, 14, 21,42
\Factors of 54: 2, 3, 6, 9, 18, 27, 54
\Identify the greatest common factor.
\The greatest common factor of 42 and 54 is 6.
\![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step2.JPG\")
Method 2:
\Write the prime factorization of each number.
\42 = 2 × 3 × 7.
\54 = 2 × 3 × 3 × 3.
\The GCF is the product of the common prime factors in each number.
\GCF = 2 × 3 = 6.
\The greatest common factor of 42 and 54 is 6.
\![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
The greatest common factor of 42 and 54 is 6.