Greta to see that many people are digging the .pdf
I too suck at math, apart from some basic stuff. But compared to a pre-schooler, i am really bad, hahaha
If you want to know where i found it. I was on Amazon, looking at the Musimathics books. I looked at Volume 1, saw the review for it. And the guy who reviewed it, said that Musimathics was a bit of a waste of money, mainly because of errors and the such.
Then said about this .pdf, and how it is better, plus free.