see, to make a 5-letter word , 5 places are to be filled ___ ___ ___ ___ ___ 1st 2nd 3rd 4th 5th the first place can be filled in 5 ways (s,p,e,l,l) 2nd place in 4 ways. 3rd place in 3 ways. 4th place in 2 ways. 5th place in 1 way. now , ther are 2L's. hence total no. of words that can be formed=(5*4*3*2*1) / 2*1