Choose the odd number: In 39, 83, 78, and 52, three numbers are multiples of 13; one number is not and is also prime. Identify this distinct number.

Introduction / Context:
Spotting a specific divisor often solves a classification item quickly. Here we focus on 13.

Given Data / Assumptions:

• Numbers: 39, 83, 78, 52.
• Fact: 39 = 3 * 13, 78 = 6 * 13, 52 = 4 * 13.

Concept / Approach:
Identify multiples of 13 and isolate the remainder.

Step-by-Step Solution:

Verification / Alternative check:
13 * 6 = 78, 13 * 4 = 52, 13 * 3 = 39. Nearest to 83 are 78 and 91; hence 83 is not 13k, and trial division up to sqrt(83) confirms primality.

Why Other Options Are Wrong:
They are exact multiples of 13 and so share a property that 83 lacks.

Common Pitfalls:
Assuming “larger” means composite; size alone is irrelevant.

Final Answer:
83 is the odd number.