Bunuel
If c is a positive integer less than 10 and n = 9446 + c, then what is the value of c?
(1) n is divisible by 5.
(2) n is divisible by 9.
Kudos for a correct solution. 800score Official Solution:As c is a positive integer less than 10, we are considering n to be an integer from 9447 to 9455 inclusive. Let’s consider the statement (1). For n to be divisible by 5, the last digit must be 0 or 5. So n can be 9450 or 9455. The corresponding values of c are 4 and 9. Two possible answer choices mean that we don’t have sufficient information using the statement (1) by itself.
Let’s consider the statement (2). For n to be divisible by 9, the sum of digits must be divisible by 9. If the first three digits are 944, then the sum will be an integer from 9 + 4 + 4 + 7 = 24 to 9 + 4 + 4 + 9 = 26 inclusive. Obviously, none of these, 24, 25, or 26, is divisible by 9.
If the first three digits of n are 945, then the sum will be an integer from 9 + 4 + 5 + 0 = 18 to 9 + 4 + 5 + 5 = 23 inclusive. Obviously, only 18 is divisible by 9, which yields 4 as the only possible value of c. Therefore the statement (2) by itself is sufficient and
the correct answer is B.