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 ...

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 computers). In quality circles, there’s a ...