Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
Home  >>  CBSE XI  >>  Math  >>  Permutations and Combinations
0 votes

The number of 5-digit telephone numbers having one of their digits repeated is

$\begin{array}{1 1}(A)\;90,000\\(B)\;10,000\\(C)\;30,240\\(D)\;69760\end{array} $

Can you answer this question?

1 Answer

0 votes
Total number $N=10^5$
Total number without repeated digits =$N_1=10\times 9\times 8\times 7\times 6$
Total no with repeated digits =$N-N_1$
$\Rightarrow 10^5-10\times 9\times 8\times 7\times 6$
$\Rightarrow 69760$
Hence (D) is the correct answer.
answered May 16, 2014 by sreemathi.v

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, AIPMT Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App