Question

Ten different letters of an alphabet are given, Words with five letters are formed from these given letters. The number of words which have at least one of their letter repeated is

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

Answer 1

Answer: (A)

$69760$

Answer 2

Reqd. number of ways $=10^{5}-\,10p_{5}$
$=100000-10\times9\times8\times7\times6$
$=100000-30240=69760$.