labeling versus combination formulas

CFA Level I
#1

So the way I’m reading both of these, there’s no discernable difference between the multinomial formula (labeling) and the combination formula, other than that the labeling can handle more than two groups.

According to the material, you’re supposed to use the combination formula when you have exactly two groups. But, for example, taking 9 items selected in groups of 5 and 4, both formulas will reduce to the following as far as I can tell:

9!/(5! 4!)

Is there some point where the combination formula gives a different answer than the usual labeling method?

#2

They’re the same.

#3

no difference at all? Why clog up the book with two formulas instead of one easy one?

#4

No difference at all.

I cannot answer your second question.

#5

When order matters, use permutation.

If it does not, use combination.

Don’t use your hand to calculate, your calculator has a build in function.

It is not hard.

#6

Yeah just use the nCr and nPr button on the BA II.