A permutation of a set of distinct symbols is an arrangement of them in a line in some order. For natural numbers n and r, with r <= n, an r-permutation of n symbols is a permutation of r of them, that is, an arrangement of r of the symbols in a line in some order.

           n!
P(n,r) = --------
         (n-r)!

A combination of a set of objects is a subset of them. A subset of r objects is called an r-combination or a combination of the objects taken r at a time.

            n!
C(n,r) = ----------
         (n-r)!*r!

	Example on Permutations:
	You have 8 marbles: 3 blue and 5 assorted color (non-blue) marbles.  If there are 8 boxes, how
	many ways can the boxes be filled given one marble per box?

	Solution
	The number of permutations of 8 distict marbles would be P(8,8).  Then we must subtract the number
	of permutations of the non-distinct marbles which is 3!.

		P(8,8)    8!
		------ = ---- = 6720
		  3!      3!

	Example on Combinations:
	Suppose that there are 3 groups: a 10 students, 5 professors, and 3 regents.  How many ways are there
	to make a committee of 2 students 2 professors and a regent?

	Solution
	If you break the question down, you must choose 2 students, 2 professors, and one regent implies the
	answer.  Using the multiplication rule, we combine these choices.

                                          10!	   5!      3!
            C(10,2) * C(5,2) * C(3,1) =  ----- * ----- * ----- = 1350	
                                          8!2!	  3!2!    2!1!

Using these two principles one should be able to solve the following question.