A thief steals an ATM card and must randomly guess the correct pin code that consists of four digits (0 through 9) that must be entered in the correct order. Repetition of digits is allowed. What is the probability of a correct guess on the first try?

The lowest value he'd be able to produce is 0000. The highest value he'd be able to produce is 9999. This means that the thief would have to select the correct pin out of 10,000 combinations. So his chances of selecting the correct pin on his first try would be:

1/10,000

{1 out of 10,000}