Can someone pls show that
nCr = n(n-1)(n-2) ... (n-r+1)
r(r-1)*...*2*1
or do you mean something else?
Choosing from distinct elements, the first may be choosen in ways the second in down to the -the in ways, so there are ways of doing the selection, but as each combination appears in these choices in ever permutation we are counting each combination r! times so the number of combinations is:
RonL