Why are credit/debit card pin numbers just 4 digits?
Is it because we are so bad at remembering things that that is the limit to our daily memory allowance? Can we not remember five digits or six digits? Interestingly you will note that many alarm systems are also just four digits – again with the four – what is going on here?
Tags: credit card, debit card, pin number
It's probably the memory thing. People remember big numbers by dividing them into sets. Like 20 40 for 2040, or ...