Choose the odd number: Among 15, 27, 37, and 39, three are multiples of 3 while one is not. Identify the non-multiple of 3.

Introduction / Context:
This set separates multiples of 3 from a single non-multiple, which is the odd item.

Given Data / Assumptions:

• Numbers: 15, 27, 37, 39.
• Divisibility-by-3 via digit-sum rule.

Concept / Approach:
Apply the digit-sum rule quickly, then confirm the outlier.

Step-by-Step Solution:

Verification / Alternative check:
37 is prime; 15, 27, and 39 are all divisible by 3 directly.

Why Other Options Are Wrong:
They are consistent multiples of 3.

Common Pitfalls:
Assuming “ends with 7” implies special divisibility; use the proper rule.

Final Answer:
37 is not divisible by 3 and is the odd number.