I bought Spivaks book on calculus, and also "how to prove it". I am just doing this for fun, not for school. On an old thread I remember reading I should learn to do proofs first before moving on to Spivak. I wont be doing this for a few months because I am busy studying for CFA exam, but I just flipped through how to prove it, and on page 2 it starts talking about intergers. I dont know what an interger is (Well I know its the area under a curve but thats about it). Should I read Spivak first?