## Counting with Identical Items

Summary

The content provides a comprehensive guide on how to approach counting problems on the GRE, specifically focusing on arrangements involving identical items.

- Introduces the concept of counting arrangements with identical items, highlighting the need for a special approach.
- Explains the process of calculating arrangements using factorials, with examples including arranging books on a shelf.
- Presents the 'Mississippi rule' for cases with multiple sets of identical items, offering a formula for calculating arrangements.
- Provides a practice problem to apply the concepts learned, reinforcing the method of dividing the total factorial by the factorials of identical items.
- Emphasizes the importance of listing and counting as a strategy to understand and solve counting problems.

Chapters

00:01

Introduction to Counting Identical Items

00:28

Calculating Arrangements with Factorials

03:16

The Mississippi Rule

04:31

Practice Problem and Summary