Unit 3 · Counting

Chapter 3.3

Arrangements and Overcounting

The fastest way to count is often to count too many on purpose, then divide by how many times each one was counted.

lesson 15 of 42

By the end

  1. 01Count arrangements with restrictions using blocks and gaps
  2. 02Divide out overcounting from identical items, unlabeled groups, and rotations
  3. 03Count arrangements where nothing stays in its original place

In unit 3

  1. 3.1Multiply or Add?
  2. 3.2Count What You Don't Want
  3. 3.3Arrangements and Overcounting
  4. 3.4Choosing, Pascal, and Stars and Bars
  5. 3.5Counting Two Ways
  6. 3.6Too Few Boxes
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