Combinations
Combinations are permutations when the order doesn’t matter.That is when you just need to choose a certain number of items from a list. For example, when choosing a combination from a menu, you choose a couple from several, usually 2 from the 7 listed or similar. It doesn’t matter which way you list them to the server, they will often be put on the same plate.When you are choosing r items out of the n items, you will use the combination formula: nCr = n!/[(n-r)!r!]
The following video goes over Combinations and is about 6.5 minutes.