Answer
$8$
Work Step by Step
Factor each number completely to obtain:
$56 = 2 \cdot 2 \cdot 2 \cdot 7
\\64 = 2 \cdot 2 \cdot 2 \cdot 2 \cdot 2 \cdot 2$
Since three 2s are common to both, the greatest common factor of the two given numbers is:
$2 \cdot 2 \cdot 2 = 8$
