Difficulty: Easy
Correct Answer: 210
Explanation:
Introduction / Context:
Odd-one-out questions often test a single property shared by most options while exactly one violates it. Here, the property is divisibility by a fixed integer (16). Recognizing factors and applying quick divisibility checks help you eliminate distractors efficiently.
Given Data / Assumptions:
Concept / Approach:
For any integer n, n is divisible by 16 if n / 16 is an integer with remainder 0. Because 16 = 2^4, another way is to check whether the number has at least four factors of 2 (i.e., divisible by 2, 4, 8, and 16). Mental division or factorization works well here.
Step-by-Step Solution:
Check 272: 272 / 16 = 17 → integer → divisible by 16.Check 240: 240 / 16 = 15 → integer → divisible by 16.Check 304: 304 / 16 = 19 → integer → divisible by 16.Check 210: 210 / 16 = 13.125 → not an integer → NOT divisible by 16.
Verification / Alternative check:
Prime-factor viewpoint: 272 = 16 * 17 has 2^4; 240 = 16 * 15 has 2^4; 304 = 16 * 19 has 2^4. Meanwhile, 210 = 2 * 3 * 5 * 7 has only one factor of 2, far short of 2^4, confirming it is not divisible by 16.
Why Other Options Are Wrong:
Common Pitfalls:
Candidates sometimes test only divisibility by 2 or 4 and stop early; being even or divisible by 4 does not guarantee divisibility by 16. Always confirm through division by 16 or ensure four factors of 2 are present.
Final Answer:
210
Discussion & Comments