How many different 10 letters words can be formed from the letters in the word
"IMMUNOLOGY"?
If it were "IMmUNOLoGY", where we could tell the difference between the
2 M's and between the 2 O's, the answer would be 10!.
However since we cannot tell them apart, we must divide by the number
of ways the 2 M's can be arranged in each permutation, which is 2!, and
also we must divide by the number of ways the 2 O's can be arranged in
each permutation, which is also 2!.
Answer: 
Edwin
