Classification – Odd one out (divisibility by 6) Exactly three of the numbers below are divisible by 6 (both even and divisible by 3). Identify the number that is not divisible by 6 and mark it as the odd one out.

Introduction / Context:
Divisibility by 6 requires two simultaneous conditions: divisibility by 2 (evenness) and by 3 (digit-sum multiple of 3). This dual-check framework is a frequent theme in classification items because it forces candidates to apply two quick rules instead of one.

Given Data / Assumptions:

• Candidates: 120, 72, 108, 98
• Goal: find the sole non-multiple of 6.

Concept / Approach:
First check evenness; then check the digit-sum for divisibility by 3. If both hold, the number is a multiple of 6. If either fails, it is not a multiple of 6.

Step-by-Step Solution:
120 → even; 1 + 2 + 0 = 3 → divisible by 3 → 120 is a multiple of 6.72 → even; 7 + 2 = 9 → divisible by 3 → 72 is a multiple of 6.108 → even; 1 + 0 + 8 = 9 → divisible by 3 → 108 is a multiple of 6.98 → even; 9 + 8 = 17 → not divisible by 3 → not a multiple of 6.

Verification / Alternative check:
Direct division confirms: 120/6 = 20, 72/6 = 12, 108/6 = 18 (all integers). 98/6 = 16 remainder 2, not an integer. Methods agree.

Why Other Options Are Wrong:

• 120: Satisfies both conditions; not odd one out.
• 72: Satisfies both conditions; not odd one out.
• 108: Satisfies both conditions; not odd one out.
• None of these: There is a clear unique non-multiple (98).

Common Pitfalls:
Stopping after the evenness check. Remember: 6 requires both 2 and 3 as factors.

Final Answer:
98