Using the integer coefficient vs. the float coefficient would be a decision of "fast fit" vs. "best fit". Integer multiplication would be a little faster but you'd waste a few more bytes in some circumstances. Space vs. time, the classic tradeoff in computerized problem solving. Of course that decision is a "micro-optimization" anyway - unless n is really freaking big - and micro-optimizations are mostly frowned upon these days. On the other hand Musashi said that the true tests of skill are "the small, fine works."
I've found that most of the programming one does as a sysadmin doesn't strain the "advanced" fields of programming theory and it doesnt't require any math at all. There's a lot of "glue" programming, which often requires one to be clever but not very deep. And in my case I do a lot of patches to free software, which makes me feel good but again these are very small hacks. There is one large piece of software done for the company in which I am applying increasingly sophisticated techniques. And it's working out well which makes me feel good about being able to use that knowledge, but I'd like to do that more often than this job really requires. I mean I could structure my solutions in ways that would require a lot of custom code but that's hardly good business. It's better in the long run to take established (free software) tools, shim them together with a little code where needed, and set it loose. That's why I love well structured modular softwares (like Apache) cause they readily lend themselves to that sort of approach.