Question

Ten different letters of an alphabet are given, words with five letters are formatted from these given letters. Then the number of words which have at least one letter repeated is

• A. $69760$
• B. $30240$
• C. $99784$
• D. None of these

Answer 1

Answer: (A)

$69760$

We need to form number of words which have at least one letter repeated.

So, it is equal to $=$ Total $-$ No letters are repeated
$={10}^5-(10\times 9\times 8\times 7\times 6)$
$=69760$