Question

You must choose a new 4-digit ATM pin number from the numbers 5, 0, 3, and 8. The pin cannot start with 0. How many 4-digit pin numbers are there?

Answer 1

Since the first digit cannot be cero, we have:

3 possibilities for the first digit

4 for the second, third and fourth

The total number of combinations is:

$3\times4\times4\times4=192$