let n = ABCD

tens digit = C

1. 10n = ABCD0
given, hundreds digit = 6 (or) C = 6 - sufficient

2. tens digit of n+1 = 7.

consider CD = 69 -> CD+1 = 70 -> C=6 (or)

consider CD = 71 ->CD+1 = 72 -> C = 7

2 cases possible - insuff.

A IMO

Anurag@Gurome wrote:

nidhis.1408 wrote: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.

Statement 1: If we multiply any positive integer with 10, all the digits of the of the integer shifts one place to the left. Hence, tens digit of n is same as the hundreds digit of 10n.

Sufficient

Statement 2: Say, n = 69 ---> (n + 1) = 70 --> Tens digit are different
But if n = 68 ---> (n + 1) = 69 --> Tens digit are same

Not sufficient

The correct answer is A.

Hello

Thanks for your response. Kindly confirm one thing. The question states "2. the tens digit of n+1 is 7." but if we take n = 68 ---> (n + 1) = 69 (in this case 10's digit is not 7).

n = 69 ---> (n + 1) = 70
n = 70 ---> (n + 1) = 71

Please correct me if I am wrong but is the above what you wanted to write?

Thanks

Whenever you multiple by 10, you are moving the digits to left hand side. So after multiplication the tenth digit becomes hundredths digits. Hence A gives the answer.

B) units digit can be 9 and this will affect the tenth digit. It can be 6 or 7.