Hello i'm having trouble with my homework and i can't understand it very well. i just want to know what is p(6, 2). my subject is on permutations.

6!/(6 - 2)! = 30

The calculator provided computes one of the most typical concepts of permutations where arrangements of a fixed number of elements r, are taken from a given set n. Essentially this can be referred to as r-permutations of n or partial permutations, denoted as nPr, nPr, P(n,r), or P(n,r)among others. In the case of permutations without replacement, all possible ways that elements in a set can be listed in a particular order are considered, but the number of choices reduces each time an element is chosen, rather than a case such as the "combination" lock, where a value can occur multiple times, such as 3-3-3. 

Is there a picture of a graph or whatever that goes along with this?