Dave Ramsey, the personal finance radio host and author, has long compared credit cards to cigarettes, calling them “the ...

All mainstream credit card numbers obey a mathematical trick designed to catch the most common typos. It’s called the Luhn algorithm, named after IBM researcher Hans Peter Luhn, who patented it in ...

Credit card balances that never seem to shrink are usually a math problem, not a moral failing. When interest rates on ...

A few weeks ago, I was about to pay the HVAC technician who had repaired my home’s heat pump. Out of habit, I pulled a credit card from my wallet — I figured I’d earn rewards on this pricey ...