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Permutation Formula
publish date: 2026/05/23 05:43:42.474443 UTC
The number of permutations (arrangements) of \(n\) different things taken \(r\) at a time is given by \({}^nP_r =\) .
Correct Answer
$\frac{n!}{(n-r)!}$
Explanation
The permutation formula is \({}^nP_r = \frac{n!}{(n-r)!}\). For example, \({}^5P_3 = \frac{5!}{2!} = \frac{120}{2} = 60\).
Reference
Introduction to Differential Calculus (Systematic Studies with Engineering Applications for Beginners) - 2012