Question

10 different letters of a alphabet are given. Words with 5 Letters are formed from these given letters, then the numbers of words which have at least one letter repeated is

• A. $69760$
• B. $30240$
• C. $99748$
• D. none

Answer 1

The correct option is A $69760$

Required number of words == Total number of words - Total number of words in which no letter is repeated
= ${10}^5-P^5$
= $1000000-10\times 9\times 8\times 7\times 6$
= $1000000-30240$
= $69760$