So degree of unsaturation, given by the Greek letter omega, gives us the total number of pi bonds and or ring structures for that given molecular formula. And the formula to find degree of unsaturation is given by this guy here. So two N plus two minus x, and the whole thing divided by two, where N represents your number of carbons and x represents your number of hydrogen atoms. Now, whenever we're using this formula and we're trying to determine degree bond saturation, we have to follow three important rules. Rule number one, replace all halogens with hydrogens. Rule number two, whenever you're given a molecule or compound with oxygens or sulfur, omit the oxygens and sulfur in your formula.