JEE Main 2018MathematicsPermutation CombinationMediumMCQ

JEE Main 2018 — Permutation Combination Question with Solution

JEE Main 2018 (15 Apr)

Question

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 :

Choose an option

Show full solutionCorrect option: B
Correct answer
B7

Step-by-step explanation

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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About this question

This is a previous-year question from JEE Main 2018, covering the Permutation Combination chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.