Oxidation Number

[Ian Williams 2I]

Hey guys,
I was running through practice problems on compound naming, and I realized that I basically have no idea how to find oxidation number (embarrassing, I know.) Can someone please either explain it to me or point me to some resources that will help out? I looked through my notes and didn't really see too much that clarified it. Thanks!

[Caroline Schick 1I]

For oxidation numbers, first determine the charge of the anion by looking at the periodic table, and if there is a subscript, multiply the charge by the subscript. Then take your cation/transition metal and find the charge that will make the compound neutral, or equal to the overall charge of the compound. After finding the charge of the cation/transition metal, this is the oxidation number, so just make sure to write it in roman numerals and then you are done.