9. A museum has 5 entrances, and each entrance can only allow one person to enter at a time. A delegation of 20 people goes to visit. How many ways are there for them to enter the museum?
9. Each scheme for entering the library corresponds 1-1 to the full permutation of 5 identical white balls and 9 distinct red balls, and the number of permutations is $C_{14}^{5} \cdot P_{9}^{9}$.