Answers

2014-05-02T12:15:29+05:30
Each of the arrangement which can be made by taking some or all of a number of thing is called a permutation
n number of things can be selected in n! ways
then
P_{r}^n is Number of permuatations of n different things taken r at a time
P_{r}^n= \frac{n!}{(n-r)!}=n(n-1)(n-2) ....(n-r+1)
Post ur questions it depends mainly on question
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  • Brainly User
2014-05-02T14:46:47+05:30