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OG12 - DS 167

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OG12 - DS 167

by vidhya16 » Fri Apr 22, 2011 9:15 am
All,

If n is the positive integer, what is the tens digit of n.

(1) The hundreds digit of 10n is 6.
(2) The tens digit of n + 1 is 7.


I didnt understand the explanation provided in OG12. Can anyone give good explanation?

Ta
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by pemdas » Fri Apr 22, 2011 10:37 am
given: n {integer}>0, find the tens digit of n?

st(1) The hundreds digit of 10n is 6, this is Sufficient alone, because the tens digit of n is 6;
st(2) The tens digit of n + 1 is 7, this is Not Sufficient alone.

IOM a


I didnt understand the explanation provided in OG12. Can anyone give good explanation?

Ta[/quote]
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by manpsingh87 » Fri Apr 22, 2011 10:41 am
vidhya16 wrote:All,

If n is the positive integer, what is the tens digit of n.

(1) The hundreds digit of 10n is 6.
(2) The tens digit of n + 1 is 7.


I didnt understand the explanation provided in OG12. Can anyone give good explanation?

Ta
1) consider any no. say 12, when we multiply it by 10, we get 120, i.e. unit at the ten's place got shifted to 100's place..!! now since hundred's digit of 10n is 6, therefore in "n" ten's digit must be 6..!! hence 1 is sufficient.

2) ten's digit of n+1 is 7, consider n=69; 69+1=70, here ten's digit is 6 in n, now consider n=70 we have n+1=71, here ten's digit is 7 in n, therefore 2 alone is not sufficient to answer the question..!!!

hence A
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by vineeshp » Fri Apr 22, 2011 10:42 am
Yes it is indeed A.

If the hundreds digit of 10n is 6, then it means 10n is equal to or greater than 600 and less than 690.

So if u divide this number by 10 (I mean divide 10n by 10 to get n) we get a 2 digit number with 6 in the ten's place.

So stmt 1 is sufficient.

--------

Stmt 2 is not sufficient because if tens place of n+1 is 7

it can mean that n is 69 or any number up to 78. This means n+1 will give you tens place as 7. So not sufficient n's tens place can be 6 or 7.
Vineesh,
Just telling you what I know and think. I am not the expert. :)
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by vidhya16 » Sat Apr 23, 2011 9:34 am
Thanks Guys. I was confused with the term 10n. I consider n between 600 - 699 and didnt relate to n/10 or n * 10. Now it is clear. Thanks for helping out.

Ta
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