There are many opportunities to use 'four-digit PIN numbers' in our daily lives, such as credit card PIN numbers, smartphone passcodes, and PC unlock codes. In all cases, we should use four-digit ...

Four-digit numbers can be partitioned into ones, tens, hundreds and thousands. Understanding the value of each digit makes it easier to compare numbers using the less than (<), greater than (>) and ...

A study of over 216 million four-digit PIN codes shows which combinations are chosen particularly frequently and are therefore the easiest to crack. A recent analysis of over 216 million four-digit ...