Distributive property

The distributive property says that multiplying a sum by a number is the same as multiplying each part and adding: a × (b + c) = a × b + a × c.

It also works backwards, which is how a sum is factored. When both parts share a factor, pull it out front: 36 + 8 = 4 × 9 + 4 × 2 = 4 × (9 + 2). The shared factor 4 is the greatest common factor of 36 and 8.