Permutations / Arrangements (Leaving Cert Mathematics): Flashcards

Arrangement of objects in a specific order

Order of selection matters

Product of all positive integers up to $n$

$n \times (n-1) \times (n-2) \times \ldots \times 1$

$n!$

$\frac{n!}{(n-r)!}$

$\frac{n!}{p_1! \times p_2! \times \ldots \times p_k!}$

$24$

$60$

$3$

Reduces total permutations

Counting problems and probability