Difficulty: Easy
Correct Answer: 44
Explanation:
Introduction / Context:Number-classification problems often ask you to separate prime numbers from composite numbers. Primes have exactly two positive divisors (1 and the number itself). A composite number has additional divisors beyond 1 and itself. Here, three options are prime; one is composite. Your job is to spot the composite number.
Given Data / Assumptions:
Concept / Approach:Test each number for small prime divisors (2, 3, 5, 7, 11). Even numbers greater than 2 are immediately composite. Odd numbers not divisible by small primes are likely prime (and can be confirmed by checking up to their square roots).
Step-by-Step Solution:
17 → not divisible by 2, 3, 5; sqrt(17) < 5 → prime.44 → even and > 2 → composite (44 = 2 * 22 = 4 * 11).29 → not divisible by 2, 3, 5; sqrt(29) < 6 → prime.13 → not divisible by 2, 3, 5; sqrt(13) < 4 → prime.Verification / Alternative check:The parity shortcut flags 44 instantly as composite because all even integers above 2 are composite. Cross-check by factorization: 44 = 2 * 2 * 11, confirming more than two divisors.
Why Other Options Are Wrong:
17 has only two divisors (1 and 17) → prime.29 has only two divisors (1 and 29) → prime.13 has only two divisors (1 and 13) → prime.Common Pitfalls:Confusing “odd” with “prime” is a common error; many odd numbers are composite. Always apply divisibility tests rather than relying on parity alone.
Final Answer:44 is the composite number and hence the odd one out.
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