actually we start numbering by minimising the number of highest order addition, which is the isobutyl, if it gets same number regardless, then we try to minimise the sum of numbers, so i think it should be called
5-(isobutyl)-5,6,6,7,8-penta-ethyl-8-methyl-decane (I am assuming hydrogen's are present, just not represented, because that usually is the case)
I may alo be wrong here, it has been 4 years since I have been required to do nomenclature myself
Ah, my chemistry department taught me the other way around. I distinctly remember the phrase "methyl-ethyl" being thrown around a bit. Additionaly, we were taught to be more specific about isomers, hence me using butan-2-yl instead of isobutyl.
Then again, scientists often disagree strongly about things like this, so we could both be right. Also, there's a good chance this is just the A-Level specification being weird. I left my old textbook at my student flat, though, so I won't be able to check for a couple of weeks.
I could also be downright wrong myself.
As for the hydrogens, I had assumed they were not present, and that this lossane molecule is an ion with a charge of -50. This is borderline impossible to achieve in real life, of course.
As someone who paid enough attention in highschool chemistry to get a B, and occasionally watches Nile(red/blue) and E&I videos.... I know some of these words/symbols!
It basically comes down to finding the longest chain of carbons, then you number each of the carbons on that chain and list off things that are attached to each of them. For example, 1 carbon = methyl, 2 carbons = ethyl, etc.