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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 a and b are integers, is ab divisible by 24? tagged by: AAPL ##### This topic has 1 expert reply and 0 member replies ### Top Member ## If a and b are integers, is ab divisible by 24? If a and b are integers, is ab divisible by 24? (1) a = 12x, where x is an integer. (2) b = 8x, where x is an integer. The OA is C. I don't have clear this DS question. Please, can any expert help me with it? Thanks. ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 AAPL wrote: If a and b are integers, is ab divisible by 24? (1) a = 12x, where x is an integer. (2) b = 8x, where x is an integer. The OA is C. I don't have clear this DS question. Please, can any expert help me with it? Thanks. Statement 1: We're told that a is a multiple of 12. If a = 12 and b = 1, then ab = 12, and NO, ab is not divisible by 24 If a = 24 and b =1, then ab = 24, and YES ab is divisible by 24 Not Sufficient Statement 2: We're told that b is a multiple of 8. If a = 1 and b = 8, ab = 8, and NO ab is not divisible by 24 If a =1 and b = 24, ab = 24 and YES ab is divisible by 24 Together. If a = 12x and b = 8x, then ab = 12x*8x = 96* x^2. Because 96 is itself divisible by 24, and x is an integer, 96* x^2 will always be divisible by 24, and the statements together are sufficient. (You can also think of it this way: (96 * x^2)/24 = 4 * x^2, which will have to be an integer if x must be an integer.) The answer is C. _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

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