Question

what is the formula for Permutations and Combinations?

Answer 1

permutations tend to be a "pick" of numbers: P(5,2) means 5*4 ; combo C(5,2) is just P(5,2)/2!

Answer 2

then there are others that relate to how many times something appears in the same setup and what nots, but those are the basics i believe

Answer 3

P(n,r) means n*(n-1)*(n-2)*... "r" number of times

Answer 4

P(10,7) = 10.9.8.7.6.5.4