Question

An atm personal identification number (pin) consists of four digits, each a 0, 1, 2, . . . 8, or 9, in succession.

Answer 1

An atm personal identification number (pin) consists of four digits, each a 0, 1, 2, . . . 8, or 9, in succession.

a. How many different possible pins are there if there are no restrictions on the choice of digits?

Solution: The are total 10 numbers between 0 and 9.

Also there are no restrictions on the choice of digits. Therefore, the possible number of different PINs is:

$10^{4}$

$10000$

Therefore, there are 10,000 different possibles PINs.