Oh, the bane of every gifted child's schooling career: "Show your work." I remember that! Ugh, it was awful; sometimes my brain just knew the answer and had it's own way of getting there. Being forced to use someone else's method can be downright harmful, if your method is also based on firm principals -- just different ones!
I like Cathy's idea, and I think it would work if the teacher didn't think that dd came off sounding like a know-it-all (which I, too, was exceptionally guilty of in school!). You might want to step in and ask the teacher (in a polite and non-threatening way, of course) if there was a rationale for the method or if your dd could use her way, provided it works for all the problems given and yields the same answer.
As for the remainder thing ... she might just have to suck it up and give answers with remainders. There really are some situations where remainders are useful. If it's just "bothering" your dd to answer with remainders, I'd probably advise her to do it both ways, if she really wants to. Probably what's happening is that the other kids don't know how to divide with decimals yet ... but the teacher may have a reason for wanting them to answer with remainders.
Good luck! I also ran afoul of several math teachers (and physics teachers; one who lamented my lack of work ethic and my straight-out "don't care" attitude toward physics, though I clearly had an aptitude for it) -- but then you get those great teachers who really encourage creative thinking. I hope she gets one of those next year!
