OG 12; data sufficiency; problem 167

[Pugalenthi]

If n is a 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

The answer is A.

I can understand why B is not an answer but not able to understand why A is the answer. Any help would be much appreciated.

[Pugalenthi]

I found a good explanation for this...https://www.youtube.com/watch?v=wLAbFXBq ... plpp_video

[Brent@GMATPrepNow]

If n is a 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

The answer is A.

I can understand why B is not an answer but not able to understand why A is the answer. Any help would be much appreciated.

Statement 1: the hundreds digit of 10n is 6
Notice what happens when we multiply any positive integer by 10:
34 x 10 = 340
60 x 10 = 600
128 x 10 = 1280
54629 x 10 = 546290
The tens digit in the original number becomes the hundreds digit in the new number.

So, if we're told that the hundreds digit of 10n is 6, then we know that the tens digit in n must be 6.
So, statement 1 is SUFFICIENT

Statement 2: the tens digit of n+1 is 7
case a: n=69 in which case the tens digit of n is 6
case b: n=74 in which case the tens digit of n is 7
Since we can't answer the target question with certainty, statement 2 is NOT SUFFICIENT and the answer is A

Cheers,
Brent

[Anurag@Gurome]

Refer to the post here >> https://www.beatthegmat.com/tens-digit-o ... tml#426692