PORTLAND, Ore. - With so many people in trouble with credit cards, what's the best way to protect your credit? Is it by keeping the cards or cutting them up?

Richard Gritta, a finance professor at the University of Portland, has one answer: "I would pay off the cards first and keep them open for a period of time. If you've got four or five I'd get rid of one, then wait, and look at your credit score and then get rid of another."

Professor Gritta said the formulas the credit rating companies use are secret, but he suspects they take the stance that people who cancel their credit cards are in deep financial trouble.

People who are financially in trouble, are not necessarily viewed as responsible. The act of cancelling your credit cards therefore could lower your score -- something that could hurt you by increasing your interest rates or causing a decline if you plan to apply for credit down the road.

KATU.com research turns up that the maximum number of credit cards to carry at any time is four. An additional car loan tends to lower your score, while a home loan or line of credit tends to raise it.

Meanwhile, the experts warn against cancelling the oldest cards in your stack. The credit reporting agencies -- TransUnion, Equifax and Experion -- use that "length of time" measurement to increase your score. Cancelling the oldest card may very well drop your overall score.

A secure Web site out of San Francisco, CreditKarma.com, provides a simulator that -- for free -- taps into your real TransUnion FICO score to show you exactly what would happen if you cancel your oldest card, add a new credit card or increase or decrease your credit limits. The site gets paid by the credit partners that advertise offers for people with specific credit scores.

Meanwhile, you'll find several other helpful links, including a FICO score simulator provided by BizRate.com, below.

Hotlinks

• Credit card fees: Calculate your FICO credit score here
• Sift through the fact and fiction on credit scores here
• Get your credit report, without your FICO score, for free from all three agencies