Math Bleg

Several readers commented on how my "What you should know by 18" list was pretty light on the math and science (though I hope some of the addendums in the comments helped with that). One of the issues there is that I had a hard time coming up with a good idea of what the minimum a civilized and functional person should know in these fields would be. It really was meant to be a pretty basic list. (A high school student could do all the reading on that list in under a year, I'm pretty confident.)

The other problem, however, is that although I deal with data analysis on a daily basis as part of my job, I've honestly forgotten most of the higher math I ever knew. I went through calculus in high school (I used the Saxon textbooks and did moderately well) but that's ten years behind me now. On a daily basis, I mostly just end up summing and averaging large record sets. Once in a while I do a little regression analysis: but that's just by using the crutch of trend() and forecast() functions in Excel, not through any solid remembrance of the math involved.

But this is something I've been feeling increasingly guilty about lately. And as my projects seem to get more and more mathematically intensive, one of these days it's going to come back to bite me.

So for those of you with serious mathematical chops: Can anyone recommend a good refresher book on higher math? On a practical level, it wouldn't hurt me to read up more on the kinds of business data analysis that I do on a regular basis, but at a more basic level I feel like I never fully "got" calculus and some of the other elements of higher math, although I gained the ability to get through problem sets with relative facility. I tend to be the sort of person who needs to nail the general theory in order to feel like I really understand what I'm doing at the particular level. So I'm thinking I may need something that takes something of a top-down approach. I still have my high school calculus text book sitting around, but I'm kind of wondering if I need to take a different approach.

Suggestions welcome.