So that means we have to begin on this end. So carbon number one, carbon number two, carbon number three, carbon number four. Notice in this case we have a four carbon backbone and our double bond has a one. It gets assigned a number one because our double bond begins on carbon one. If we begin number eight, our backbone, from this end, our carbon double bond will get a three. And since we want the lowest possible number value according to step two or rule two, this is how we label it.