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Counting with Identical Items

The content provides a comprehensive guide on calculating arrangements involving identical items, crucial for tackling permutation and combination questions in the GRE exam.
  • Introduces the concept of arranging n unique items and extends it to scenarios involving identical items, requiring a special approach.
  • Explains the method to calculate arrangements when some objects are identical, using the factorial formula adjusted for identical items.
  • Illustrates the concept with examples, including arranging books on a shelf with some identical copies, and applying the Mississippi rule for letters in a word.
  • Offers a practice problem to reinforce understanding of arranging items with multiple sets of identical objects, demonstrating the calculation process.
  • Emphasizes the importance of listing and counting as a strategy to conceptualize and solve arrangement problems involving identical items.
Introduction to Arrangements with Identical Items
Calculating Arrangements with Identical Items
The Mississippi Rule Explained
Practice Problem and Summary