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?

Years ago, one of my closest friends found himself staring down about $30,000 in credit card debt. He was juggling multiple cards, paying 20%+ interest, and was extremely overwhelmed. Then he ...