- How many permutations of \(\{1, 2, 3, 4, 5\}\) have \(2\) in the second place?
Fix the \(2\) in the second place and permute the remaining 4 elements for the total of \(4! = 24\) permutations.
- How many permutations of \(\{1, 2, ..., n\}\), \(n > 3\), have \(2\) in the second place and \(3\) in the third place?
Fix \(2\) in the second place and \(3\) in the third place and permute the remaining \(n - 2\) elements for the total of \((n - 2)!\) permutations.