Bunuel
If the product of all the digits a 3-digit positive integer n is 160, then what is hundreds digit of n ?
(1) The units digit of n is an even number .
(2) The hundreds digit of n is an odd number .
Target question: What is hundreds digit of n? Given: The product of all the digits a 3-digit positive integer n is 160Let's find the prime factorization of 160
160 = (2)(2)(2)(2)(2)(5)
Since each digit cannot be greater than 9, we can see that the three digits must be
4, 5 and 8.
This means that there are only six possible values of n:
458, 485, 548, 584, 845, and 854 Statement 1: The units digit of n is an even number When we check the
six possible values of n we see that four of the six possible values satisfy statement one.
Consider these two possible cases:
Case a: n =
458. In this case, the answer to the target question is
the hundreds digit of n is 4Case b: n =
548. In this case, the answer to the target question is
the hundreds digit of n is 5Since we cannot answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: The hundreds digit of n is an odd number Since the three digits must be
4, 5 and 8, it MUST be the case that the hundreds digit is 5
So, the answer to the target question is
the hundreds digit of n is 5Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent