However, if you have a weak background in math and want to get up to speed before going into calculus and beyond, I have 2 suggestions.
1) Lial's Basic College Math is adequate and will get you up to speed.
2) Serge Lang's "Basic Mathematics" is great and will cover all you need to go into a rigorous theory based college math class.
 http://www.amazon.com/s?ie=UTF8&field-keywords=lials%20basic... The editions basically the same... pick the cheapest
<discl>I'm the author</discl>
I agree that you don't need to read thousands of pages to learn calculus. However, I don't want to stop at calculus. Basically, what I'd really love to have is a "mother of all maths textbook" -- a thick and heavy tome that compacts information from all the other thick and expensive books (which I'm never going to read) and different fields of mathematics. With enough detail that you can actually learn from it -- so it shouldn't be just for review and looking up formulas you couldn't memorize. I'd like to call it a reference book I can forever keep in my bookshelf (under my bed) and always look in it if I'm unsure about something...
If someone has book suggestions, I'm all eyes.
For a more "math for general culture" I'd recommend this one: http://www.amazon.ca/Mathematics-1001-Absolutely-Everything-... which covers a lot of fundamental topics in an intuitive manner.
I have both books on the shelf, but not finished reading through all of them so I can't give my full endorsement, but from what I've seen so far, they're good stuff.
Do you plan to release an ePub or mobi-format book? I'd prefer to read it on my ereader, and PDFs don't reflow on smaller screens.
Do you know of any math books that are available as .epub? I'd like to see how they implement equations... PM me if you would like to be a beta tester.
Her department is "Industrial & Systems Engineering", she doesn't need to know much more math than how to do arithmetic and a Chai squared. Not that I know more math than she does, it's just not a true part of the mathematical disciplines. She and I probably both just use the tools handed to us and don't understand the beauty or the ugliness. One of the big problems with math today is that nobody understands that arithmetic isn't math. It would be like a baseball player being called a woodworker because she used a wooden bat.