Gmat_mission wrote:Given that R is a positive three-digit integer, what is the hundreds digit of R?
1. The hundreds digit of 3R is 8
2. (R+1) results in a number with the hundreds digit of 9.
[spoiler]OA=C[/spoiler].
Experts, may you help me here? I would like to know how to solve this DS question.
Given: R is a positive three-digit integer
We have to determine the hundreds digit of R.
Let's take each statement one by one.
1. The hundreds digit of 3R is 8.
=> 3R can be a 3- or a 4-digit number. Example, Say R = 299, then 3R = 899 (a 3-digit number); again say, R = 600, then R = 1800 (a 4-digit number).
We cannot determine the unique value of the hundreds digit of R. Insufficient.
2. (R +1) results in a number with the hundreds digit of 9.
=> R can be any number between 899 to 998. We cannot fix the unique value of the hundreds digit of R. Insufficient.
(1) and (2) together
R cannot be 899 as 3R = 899*3 = 2697; we see that the hundreds digit of 3R is not 8! Thus, R must be a number between 900 to 998. The unique value of the hundreds digit of R = 9. Sufficient.
The correct answer:
C
Hope this helps!
-Jay
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