Ren-no, not excel, the old fashioned way. Drawn out on paper.
And MOSW-Stoich is my worst part as far as chemistry goes.
I've often thought I make for a pretty unlikely individual to have ended up taking up chemistry for a hobby, since I'm dyscalculic as hell. And sometimes, not always but the more complex rearrangements and cycloadditions, tautomerizations can go a bit skewy in my mind's eye. But it seems, being a spazz counts for something, if one wants to succeed badly enough, that is sure as hell IMO a pretty strong driving force.