Question 1009867
20p3 = n! / (n-x)! = 20! / 17! = (20 * 19 * 18) * 17! / 17! = 20 * 19 * 18 = 6840


look at it another way.


there are 20 ways to pick a forward.
once the forward is picked there are 19 ways to pick a center.
once the center is picked there are 18 ways to pick a guard.


the number of possible ways is therefore 20 * 19 * 18 = 6840.