Unit 3 · Counting

Chapter 3.5

Counting Two Ways

If two different counts describe the same set, they must be equal, and that equation is often the whole solution.

lesson 17 of 42

By the end

  1. 01Count one total two ways and set the counts equal
  2. 02Match a hard set one-to-one with an easy one

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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