5th grade
posted by kristi .
whats the gcf of 16 and 42 why

The School Subject is NOT 5th Grade. Perhaps MATH would get you a math teacher to read y ur post and answer it. In the meantime, you might search through some of the following links:
http://search.yahoo.com/search?fr=mcafee&p=what+is+the+gcf+of+16+and+42+%26+why
Sra 
It's 2, because it's the largest whole number that can be divided by both of those numbers.