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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## If n is a positive integer, is 10^n - 1 divisible by q? tagged by: VJesus12 ##### This topic has 1 expert reply and 0 member replies ### Top Member ## If n is a positive integer, is 10^n - 1 divisible by q? If n is a positive integer, is 10^n - 1 divisible by q? (1) q is not divisible by either 5 or 2 (2) q is not divisible by 9 The OA is E. Can any expert help me here? I do not know how to explain that none of the statements is enough. Thanks in advanced. ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 Top Reply VJesus12 wrote: If n is a positive integer, is 10^n - 1 divisible by q? (1) q is not divisible by either 5 or 2 (2) q is not divisible by 9 The OA is E. Can any expert help me here? I do not know how to explain that none of the statements is enough. Thanks in advanced. Statement 1 - Case 1: n = 1; q = 1. 10^n - 1 = 9; 9 is divisible by 1, so we have a YES Case 2: n = 1; q = 7 . 10^n - 1 = 9; 9 is not divisible by 7 so we have a NO. Statement 1 is not sufficient. Statement 2: We can use the same cases we used for statement 1, as neither 1 nor 7 is divisible by 9, so we can generate a YES and a NO both for statement 2 and for the statements together, meaning that even together, the statements are not sufficient. The answer is E _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

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