It depends on for what do you need to know math and how far do you want to go?
If you want to learn math to know it better for everyday life and any odd job, start with any good high school book.
If you want to learn math to truly understand it and use it in an advanced form for the sake of itself or another hard science, then... again, start from a high school book or some of those "for dummies" self-help books (no shame there, mate!)
I have worked for the past decade as a math and physics tutor for high-schoolers and undergraduates, while holding only a BA in Physics my self, and I have come to realize that people find mathematics so often so much more difficult, is that math really requires you to have a foundation, while other school subjects really don't. You can, for example, learn medieval history without knowing much about Ancient Greece. Sure, here and there they'll be gaps, but overall, you can get the picture, however math is not like that, and most often, people have just forgotten an essential piece of information, or where not in school when it was taught, or slept through just that class that would have thought them the missing piece for them to go on. Also, often some math concepts are not being said out loud, because they are thought as "easily implied", but for some people they are just not. I had a few really intelligent folks, that understood higher concepts much easier than I ever could, but overlooked some simple implications altogether, because their mind would go straight to the complicated stuff, hence making gaps in their knowledge.
Therefore, I sincerely think that (re)learning the easy basics first is essential to understand deeper and more underlying concepts about those easy basics, but also about intermediate and advanced math alike.
Therefore, learn the simpler operations and notations and arithmetic rules first, then about functions (on an elementary-school level), then about polynomials and such, and some geometry, etc
