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 ...

Choosing the right cash-back credit card can lead to some quick savings. You can earn hundreds in cash-back rewards annually based on your spending. Are you ahead, or behind on retirement?

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 ...