>zzy thinking about credit is very widespread.
No kidding. Teresa Sullivan, a bankruptcy scholar at the University of Texas, told me years ago that she'd done some experimental work with UT undergrads showing that they didn't understand the first thing about interest rates and the mystical power of compounding. They thought that as long as you paid the minimum on the credit card bill, you were ok - not understanding that it would take about 35 years to pay off the balance if you just paid the minimum. I doubt full-fledged adults could do much better.
Doug