Question 188540
With permutations the order in which the objects are arrainged is important.
nPr Arraingement of r objects selected from a total of n objects.
=9P7
=n(n-1)(n-2)*...*(n-r+1)
=n!/(n-r)! faster than the line above.
=9!/(9-7)!
=9!/2!
=9*8*7*6*5*4*3
=181440 answer.
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Ed