A total of n balls are to be put into k boxes with conditions that there will be n1 balls in box 1 ,n2 balls in box2 and so on. With nkballs being placed in box k(n1+…..+nk = n)Explain why the number of ways of doing this is n!/n1!*….*nk!.
Explain why this is just n C n1 =n C n2 when k=2.