# MDM4U Permutations 2016-02-09

We learned the term permutations today. A permutation is a unique arrangement of items.

We learned that the number of arrangements of $r$ distinct items from a group of $n$ distinct items is

$_nP_r = P(n,r) = \frac{n!}{(n-r)!}$

For homework you need to evaluate the following permutations without use the $nPr$ or $n!$ buttons on your calculator (that is, do it by hand!). After you have calculated them yourself, verify your answer using the $nPr$ button.

1. $P(10,5)$
2. $P(10,6)$
3. $P(4,2)$
4. $P(7,6)$
5. $P(7,1)$
6. $P(20,2)$
7. $P(100,1)$
8. $P(1000,3)$