Yes, I know you could do it once upon a time. But admit it. Sometimes that fourth grade, fifth grade, sixth grade math homework looks like a foreign language. When daughter gets stuck on a math problem and asks for my help, I quickly understand why the contestants on "Are you smarter than a Fifth-grader" are never smarter than a fifth-grader.
But there's a solution. I found a great mathematics review book at the bookstore. Well, no, I don't normally browse the science and math section, but I was looking for an astronomy book and stumbled upon "Math at Hand" and I'm so glad I did. it's well organized, it has a great index, and it gives short, simple, but thorough enough explanations that I really do suddenly remember how it works. This is not a great book for a student learning the concepts for the first time. There are no practice problems and minimal examples. But for an adult who is struggling to remember mathematics lessons from 20 years back, it's perfect. There is enough white space and color to keep the book relaxed and friendly without making it feel dummed down. I'm sure it took me years before I felt comfortable with ratios and fractions. I wonder if that would have been different if my teachers had had copies of "Math at Hand".