How do I add fractions with uncommon denominators? Solution First, I have to apologize for the fact that the formatting here will be hard to follow. It is not possible to set it up properly in here. I have had to show the fractions like this 1/2. I hope that isn\'t too confusing. The first step in adding fractions with different denominators is to convert them to fractions with the same denominator. Sometimes this is really easy, because one of the denominators is a multiple of the other. So, for example,.