Since order does not matter, ie Joe, Jim, and Dave is the same as say Jim, Dave, and Joe. You would use the "n choose k" formula for unique combinations...
n!/(k!(n-k)!), where n=number of possible selections and k=selections made...
12!/(6!(12-6)!)
12!/(6!6!)
924
So there are 924 possible different committees of six people from a pool of twelve people.
