<span>Since, there are 26 letters in total.</span>
So, total permutations of 26 letters in the 6 letter word will be = 26*26*26*26*26*26 = 26^6
No. of letters that doesn’t include X = 26-1 =25
Permutations of letters that doesn’t include x = 25*25*25*25*25*25 = 25^6
So, total number of permutations that includes x= total permutations of 26 letters- permutation of letters that doesn’t include x
= (26^6 - 25^6) = 64,775,151