Now, nitric acid, it contains an hmm and an O. That means we first assign to H, then we assign to O, then we assign to the N. Now our entire molecule must be neutral, so we must take that into consideration when assigning. So let's give our H a plus one according to our table. And let's give an O a minus two according to our table. So our N should be a number, such that when you add that number to one and when you subtract negative six, we get here. Why negative six?