skip to main content

counting with identical items

mike mcgarry
lesson by mike mcgarry
magoosh expert
quiz
counting
summary
the content provides a comprehensive guide on calculating arrangements involving identical items, a crucial concept for gmat preparation.
  • 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 and the letters in the name 'mississippi', to clarify the calculation process.
  • offers a practice problem to apply the learned concept, reinforcing the method of dividing the total factorial by the factorial of the number of identical items.
  • summarizes the key rule for calculating arrangements with identical items, emphasizing the importance of listing and counting as a strategy in solving counting problems.
chapters
00:00
introduction to arrangements with identical items
00:28
calculating arrangements with identical items
03:17
the mississippi rule
04:31
practice problem and summary