We start by writing each number in PRIME factor form:
56 = 2 * 2 * 2 * 7
32 = 2 * 2 * 2 * 2 * 2
Notice that the factors that are common to BOTH numbers are 2 * 2 * 2 (the product of three factors of 2).Therefore we see that the greatest common factor for the given numbers is : 2 * 2 * 2 = 8
Using this, we can write the two numbers as the product of this common factor (8) times the factors that are left on each:
56 = 8 * 7
32 = 8 * 2 * 2 = 8 * 4
We can then use distributive property to "extract" that common factor (8) from the given addition as shown below: