The problem statement, all variables and given/known data My professor set us an online quiz in IUPAC nomenclature. I managed to get all of the problems correct, except for one. The graphic shows the molecule and my attempt at a solution. http://img67.imageshack.us/img67/8673/14ne9.gif [Broken] The attempt at a solution If you can't read what I typed in, it is: "4-sec-butyl-1,1-dimethyldecane" On my first attempt at this quiz, I tried using "s-butyl" instead of "sec-butyl" but I still missed it. My professor told us it wouldn't matter whether we used s-butyl or sec-butyl, but I decided to try both just to be sure. I have also double-checked my spelling and punctuation, but it all seems to be correct. I'm certain that the group on the left is s-butyl, there are two methyl groups so it is dimethyl, and there are 10 carbon atoms in the ring structure. Plus, I think I have the numbering correct (I did have some trouble with that initially). Any hints on what I'm doing wrong would be appreciated!