I stumbled across this book by chance on Amazon while searching for something else. My two kids are in fourth and fifth grade. The fifth grader has a lot of frustrations with math, so I often need to help her. I bought this book after reading the reviews, and I am so glad I did! It simplifies math so that in the span of a few seconds, I can quickly and easily remember how to perform mathematical operations that I haven't looked at in years. I can often remember the generalities of an operation, but not the specifics. This book helps me to remember the details that time has seemingly erased.
Math was not my thing when I was growing up, though I always managed to make "Bs" and "Cs". If I'd had this book and a parent or teacher to help guide me, perhaps I would have made better grades and had more confidence. Students who are adept at math will probably find they can use this book independently. Students with weaknesses will likely need the guidance of a parent to help them along, but the beauty is that the dictionary makes it so much easier for the parents to help the student. For example, I often forget the correct terms or definitions when helping my kids with math (e.g., words like "divisor"). I find myself trying remember precisely what the divisor is since I haven't encountered that word in many years. Now, I can quickly look it up in the dictionary and confidently assist my kids with their homework, feeling certain that I'm telling them correct information.
I bought a couple of other math dictionaries targeted to students in addition to this one, thinking that I might get the best of all worlds that way, but this one is by far the best for both kids and adults. This is the book to spend your money on.