$n$ - 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 (1) 6 (2) 8 (3) 9 (4) 7
$n$ - 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\\
(1) 6\\
(2) 8\\
(3) 9\\
(4) 7