Still, there's no gold standard when it comes to card rules. If we've learned anything in the past year, it's to live within our means or even below our means — but that varies from person to person. As long as you understand your spending style, know how much you're able to pay off, and remember to keep your debt-to-credit ratio below 30 percent, you should be a good judge of how many cards you can handle. So tell me, what's your magic number? How many credit cards are stashed in your wallet?