I am assuming you are trying to pick up $r$ numbered balls from a total of $n$ balls, and you are looking for the number of ways to do this such that the ordering of the balls is relevant.
Suppose repetition is allowed, this means that you pick up one ball from the urn(?) and then put it back and then repeat the process. There are $n$ ways of doing it in the first step and for each of those $n$ ways, there are another $n$ ways of doing it in the next step and so on so forth for $r$ steps.
In the second case, when repetition is not allowed, the urn progressively loses balls, so there are $n$ ways in the first step, $n-1$ in the second, etc.