Answer: -Your credit score is calculated based on a few factors.How long you've had a card....so keeping a credit card for a long time even if you dont use it is beneficial.How much credit you have and how much of it you use. Dont go near your credit limit if you're looking for a good score. Having too much credit is bad too. So having 20 zero balance cards is not good. -That is correct. Too many cards will degrade a score, but I doubt that having four or five would make much difference. Unfortunately, only Fair, Isaac & Co. know for sure, and they aren't telling. -It's complicated. Having open lines of credit can actually help your score, especially if the've been open for a long time. However, if you have too much open credit (in relation to your income), that hurts your score. Also, opening a lot of new credit accounts reduces your score. -Your credit score is balanced between how much money you earn, and how much debt you have or potential debt you could get in.You should keep the number of cards or accounts you get to a bare minimum, and don't take every offer that comes your way. Pay off things timely.