Geometry

Question Analysis
This question involves calculating permutations of a set of objects where some are identical.
The main focus is on using the formula for permutations of multi - sets, , where is the total number of objects and is the number of identical objects.

Key Concept Explanation
The formula adjusts the total number of permutations of objects to account for the identical objects.
Without this adjustment, we would over - count the number of distinct arrangements because the identical objects can be swapped among themselves without creating a new arrangement.

Step - by - Step Solution
Here, (the total number of books on the bookshelf) and