i liked the posts i read about how some people here learned calculus at a young age, so here i don't feel as isolated as from my 14 year old friends. i tried teaching myself calculus at age 11 with help from my dad, but had difficulty because i had to learn trig and factoring trinomials first. i managed that in a few months and then i finally learned calculus and vectors in R^3. now 3 years later i have learned calculus in n variables, linear algebra, group theory, number theory, complex variables. now i am studying analysis and topology where everything is about proofs. i learn with help from my dad but he doesn't have time to teach me everything so i use his library of math textbooks. i find it difficult to learn analysis and topology because different books give different definitions and notations, and definitions is very important to use properly in proofs. my dad said that often there will be a circle of definitions for the same thing because theorems prove that they are the same, and that's fine. but i get really annoyed when several definitions say the same thing but use different terms and symbols. this is very annoying for someone trying to teach himself from books. i heard that physicists have agreed on common units (called si units i think) so that there is no confusion, so why can't they do this in math?