What is the tens digit of the positive integer r?

1. The tens digit of r/10 is 3.
2. The hundreds digit of 10r is 6.

Data Suff.-Gmat Prep 1

How can I go about solving this problem?

Your input is appreciated....

[quote="Anonymous"]What is the tens digit of the positive integer r?

1. The tens digit of r/10 is 3.
2. The hundreds digit of 10r is 6.

B

let the number be xxxx6x
stem 2 says
The hundreds digit of 10r is 6.
thus my new number will xxxx6xx
so unit digit has to be 6 in original number

from stem 1
original number xxxx6x
divide by 10 gives 3 in tens
xxx36
hence no information can be inferred

Hi instructors,
Could you please see if I have a good understanding of the problem from what I have written below? Your input is greatly appreciated....

Is statement 1 insuf. because you are dividing by a power of 10 and when you divide by a power the number of zeros decreases, since here you are dealing with a whole number and no decimal. So, the tens place becomes the units place and therefore the answer is insuf.

In statement 2 you are multiplying by a power of 10, in this case, you are adding zeros, so the 6 now becomes the tens place as opposed to the hundreds place.

The answer is B.


Thanks

correct.

interestingly, the fact that r is an integer is completely irrelevant to the solution; the properties of digits of non-integers are exactly the same as the properties of digits of integers.
there are some special facts about integers, though, because all of their decimal places are 0 (i.e., there's nothing after the decimal point of an integer, except 0000....). for instance, if x is an integer, then both the units and tens digits of 100x must be 0. etc.