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Calculating permutations

Calculating values of N permute M, including with multiplication and division

This math skill teaches how to calculate the permutation of N objects taken M at a time, using factorial expressions and solving step-by-step to simplify and evaluate complex permutations.

Learn calculating permutations

Teaching Transcript

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What is the value of this probability expression?

Let's start tackling one term at a time. We'll start on the top with 4 permute 2. That's 4 factorial, over 4 minus 2 factorial

Which works out to 12, so we can replace the term with 12.

Now let's work on the bottom with 2 permute 2. That's 2 factorial, over 2 minus 2 factorial

Since both zero and one, factorial, are just 1, our term's value is 2, so we can plug that in.

Our last term is 3 permute 2. That's 3 factorial, over 3 minus 2 factorial

Which has a value of 6

With all our terms replaced by their values, we can see that the expression has a value of exactly 1

Skill Practice

Calculating values of N permute M, including with multiplication and division

Test your understanding of calculating permutations by practicing it! Work through the below exercises to use it in practice.