## Thinking Mathematically (6th Edition)

$14$
Factor each number completely to obtain: $42 = 6(7) = 2(3)(7) \\56=8(7) = 2(2)(2)(7)$ Notice that the one factor of $2$ and one factor of $7$ is common to both factorization. Thus, the greatest common factor is $2(7) = 14$. Therefore, the greatest common divisor is also $14$.