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$n$ - 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
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The correct answer is:
7
7
Required $n$ digit numbers is $3^n$ as each place can be filled by $2,5,7$.
So smallest value of $n$ such that $3^n>900$. Therefore $n=7$.
So smallest value of $n$ such that $3^n>900$. Therefore $n=7$.
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