If n is a positive integer, what is the tens digit of n?
1. The hundreds digit of 10n is 6.
2. The 10s digit of n+1 is 7.
1. The hundreds digit of 10n is 6.
2. The 10s digit of n+1 is 7.
Target question: What is the value of n?amina.shaikh309 wrote:If n is a positive integer, what is the tens digit of n?
1. The hundreds digit of 10n is 6.
2. The 10s digit of n+1 is 7.
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
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 and the answer is A
Cheers,
Brent
