1. The number of ways of selecting r items out of n identical items is 1.

2. The total number of ways of selecting zero or more i.e. at least one item from a group of n identical items is (n+1).

3. The total number of selections of some or all out of p+q+r items where p are alike of one kind, q are alike of second kind, and rest are alike of third kind is {(p+1)(q+1)(r+1)}-1.

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