Question

What is diff between 'permutations' and 'combination'? Where to apply permutations and where to apply combination

Answer 1

Permutation:

P(n,r)=n!(n−r)!P(n,r)=n!(n−r)!

Combination:

C(n,r)=n!(n−r)!r!C(n,r)=n!(n−r)!r!

Apparently, you use combination when the order doesn't matter. Great. I see how a combination will give you all the possible well, combinations. However, I don't see what exactly does a permutation do then.