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 ...

Jason Fernando is a professional investor and writer who enjoys tackling and communicating complex business and financial problems. Khadija Khartit is a strategy, investment, and funding expert, and ...

Khadija Khartit is a strategy, investment, and funding expert, and an educator of fintech and strategic finance in top universities. She has been an investor, entrepreneur, and advisor for more than ...

A PHP package to perform operations on debit and credit cards like format, validate brand, number and Luhn algorithm. It validates popular brands like Visa, Mastercard, American Express, etc. This ...

You’re at the checkout screen after an online shopping spree, ready to enter your credit card number. You type it in and instantly see a red error message ...

Most of us carry credit cards and ATM cards. These, typically, have sixteen digits on the front. These digits are the unique account number for the card. For obvious reasons, just any sixteen digits ...

Here’s a fun trick to entertain friends and win bar bets: Guess the first number on somebody’s credit card tucked away in their wallet. You can do that because credit card numbers aren’t random. Using ...