Choose many statements with simple proofs from the textbook to learn how to do proofs. Make a note of the claims but not the evidence. Then try if you can back it up. Students sometimes attempt to prove a proposition without employing the complete premise. For example, they might say "Let x be any number". They cannot say anything meaningful; therefore, the claim is meaningless. You should avoid this pitfall. To prove a statement, first you need to know that it is true. Second, you need to come up with a proof. There are two ways to do this: reductio ad absurdum and argument from authority. With reductio ad absurdum, you assume that the statement is false and use one of its parts to conclude that something extremely bad would happen if it were true. For example, let's say you want to prove that all men are mortal. You could say that some immortal man has been born, which would be a contradiction so all men are mortal. This method can only be used with statements that are easy to refute this way. For example, if you were to use reductio ad absurdum to prove that all dogs are mortal, you would need a very large group of animals for someone to have escaped mortality by being an exception. The second way to prove a statement is through argument from authority.