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  • How to solve this problem- n-digit numbers are formed using only three digits 2, 5 and 7. The smallest value of n for which 900 such distinct numbers can be formed, is :

n-digit numbers are formed using only three digits 2, 5 and 7. The smallest value of n for which 900 such distinct numbers can be formed, is :

  • Option 1)

    6

     

  • Option 2)

    7

  • Option 3)

    8

  • Option 4)

    9

 

Answers (2)

best_answer

As we learned 

 

Number of Permutations with repetition -

The number of ways of filling r places where each place can be filled by any one of  n objects.

It is n^{r}

- wherein

Where r\geq 0

 

 

numbers=3^{n}> 900

i.e\: \: \: n=7

 


Option 1)

6

 

Option 2)

7

Option 3)

8

Option 4)

9

Posted by

Himanshu

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