Specialist Mathematics · Unit 1 · Combinatorics · Permutations (ordered arrangements) and combinations (unordered selections)

Use factorial notation.

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Solve problems that involve permutations.
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Use the notation (𝑛 𝑟) and 𝐶𝑟 𝑛 to represent the number of ways of selecting 𝑟 objects from 𝑛 distinct objects where order is not important. 𝐶𝑟 𝑛 = (𝑛 𝑟) = 𝑛! 𝑟!(𝑛−𝑟)!
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