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An n-digit number is a positive number with exactly n digits. Nine hundred distinct n-digit numbers are to be formed using only the three digits 2, 5 and 7. The smallest value of n for which this is possible is
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Correct option is B
Distinct n digit numbers which can be formed using digits 2, 5 and 7 are 3n . We have to find n so that3n≥900⇒3n−2≥100⇒n−2≥5 or n≥7So, the least value of n is 7.Similar Questions
The number of ways in which we can get at least 6 successive tails when a coin is tossed 10 times in a row, is
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