Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
0 votes

How many 7 digit numbers are there using the digits,1,2,3 and '2' should occur 2 times in each of the number?

Can you answer this question?

1 Answer

0 votes
Since 2 occur twice, to fix 2 $2^s$, we have to choose
any two places out of 7 (7digit numbers)
This can be done in $^7C_2$ ways.
Remaining 5 places can be fixed by any of the two numbers, 1or 2
This can be done in $2^5$ ways.
$\therefore$ The required number of 7 digit numbers = $2^5.^7C_2$
answered Sep 3, 2013 by rvidyagovindarajan_1

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