Need help with... naming ionic compounds...QUIZ tommarow! please help?

i have a quiz tommarrow on this material....a sample question is name this type 2 ionic compound...the first one is, " CuCl(2) " and the answer is, "copper II chloride". the teacher told me this answer which is how i know it. the next one is, " Fe(2)S(3) " and i dont know the answer, im not interested in the answer but more how to do these problems, i understand how to get the "copper chloride" part but not the "II" part, how do you determine the value of the roman numeral