Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationMiscellaneous/MixedMedium2 minQB
MathematicsMediumsingle choice

An n - digit number is a positive integer with exactly n - digits. Nine hundred distinct n - digit numbers are to be formed by using the digit 2, 5 and 7 only. The smallest value of n for which this is possible is

Options:

Answer:
B
Solution:

We must have

The least n satisfying this is 7 .

Stream:JEESubject:MathematicsTopic:Permutation & CombinationSubtopic:Miscellaneous/Mixed
2mℹ️ Source: QB

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