What you won't know is where that double bond is actually found. So the question is how do we actually determine or how do we describe the location of that double bond? Well, the way that we begin is we begin by numerically labeling, numbering these carbons. And typically we begin on the carboxylic acid side. So we have carbon one, carbon 2345, all the way to 16 in this particular case. But let's use another example.