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 ...

That long number isn't random, and it identifies more than just whose account the card belongs to. Many or all of the products on this page are from partners who compensate us when you click to or ...

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory. She reports on topics from maths and history to society and animals. Katie has a PhD in maths, ...

Computers in working order and with correct software don’t make mistakes. People, however, make plenty of mistakes (including writing bad software or breaking ...