![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
Method 1:
\Factor the each monomial.
\18 = 2 · 3 · 3.
\45mn = 3 · 3 · 5 · m · n.
\The GCF is the product of the common prime factors in each monomial.
\GCF = 3 · 3 = 9 The greatest common factor of 18 and 45mn is 9.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
The greatest common factor of 18 and 45mn is 9.