Prime factors can only be divided evenly, plus they can only have numbers that can not be 1 or itself. Well two numbers that equal 36 are 12 x 3. 3 has no factors that you can divide it by so it journey down the tree ends. Factors of 12 are 6 x 2. 2 has no other factors either so you keep going with 6. 6's factors are 2 and 3. So you just find all the factors that they all end with. In this case they are 3 and 2.
