Do you mean all the introductory mathematics books you tried fail to properly explain the notation ? Or that the notation differs from books to books ? (In my

Do you mean all the introductory mathematics books you tried fail to properly explain the notation ? Or that the notation differs from books to books ? (In my case, I learned the notation via French math textbooks, and in the first day of college/uni we litteraly went back to "There is a set of things called natural numbers, and we call this set N, and there is this one thing called 0, and there is a notion of successor, and if you keep taking the successor it's called '+', and..." etc.. But then, the French, Bourbaki-style of teaching math is veeeeeeeery strict on notations.