If \(n\) is a positive integer, what is the tens digit of \(n ?\)

[Vincen]

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 \(7.\)

[spoiler]OA=A[/spoiler]

Source: Official Guide

[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 \(7.\)

[spoiler]OA=A[/spoiler]

Source: Official Guide

Target question: What is the tens digit of n?

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
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: The tens digit of n+1 is 7
There are several values of n that meet this condition. Here are two:
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 cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT


Answer: A