Step-by-step explanation
The question wants us to determine the number of different ID cards that can be made if there are 3 digits on a car.
To do so, let us first list out all the possible outcomes. These are:
We can see that there are 10 possible digits
For the first case where no digit can be used more than once, we will have
Therefore, there are
For the second case, if the digits can be repeated, then, we will have
Then, since the numbers can be repeated, we will have