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Question: Answered & Verified by Expert
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 :
MathematicsPermutation CombinationJEE MainJEE Main 2018 (15 Apr)
Options:
  • A 9
  • B 7
  • C 8
  • D 6
Solution:
1665 Upvotes Verified Answer
The correct answer is: 7

n- digit number are formed using only three digits 2, 5 and 7 with repetition =3n.

Since, 36<900 and 37>900

So, n=7.

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