Nine different letters of alphabet are given, words with 5 letters are formed from these given letters. Then, how many such words can be formed which have at least one letter repeated ?

Number of words with 5 letters from given 9 alphabets formed =  $95$

Number of words with 5 letters from given 9 alphabets formed such that no letter is repeated is =  $9P5$

Number of words can be formed which have at least one letter repeated =   $95 - 9P5$

= 59049 - 15120

= 43929