I saw that some of them, you did not multiply the oxidation number by the subscript number. Also, you did not multiply by the coefficient number. Do we not have to multiply in order to see if it is oxidation or reduction? Also, should we multiply if we are trying to find an atom's oxidation number?
When determining oxidation numbers for the elements in any particular compound, you do NOT have to multiply by the coefficient for the individual reaction. It is important, however, to multiply the oxidation number by the amount of that atom present in the compound (the subscript). Even if I did not explicitly show it for each example, I always multiply by the subscript to make sure the overall oxidation state of the compound matches the given charge of the molecule. Hope that clears it up for you, and thanks for asking!
