We can use the simple common factor method to figure out the factors of a number. Even simple algebraic expressions with all the common variables can be solved with this method. But there are two other ways to factorize numbers and expressions that are a little more complicated than the common factor method but are needed when different variables are involved. These are the regrouping method and the identities method. With the regrouping method, we put factors that are the same into separate groups and then use each group as a factor on its own. With the identities method, we use simple algebraic identities to find the factors of an expression.