Difficulty: Medium
Correct Answer: 4993
Explanation:
Introduction / Context:
This question gives the series 14, 27, 105, 525, 4993 and asks you to identify the odd number out. The main idea is to analyze the prime factors of each number and see which one differs structurally from the rest in terms of factorization patterns.
Given Data / Assumptions:
Concept / Approach:
Prime factorization breaks each number into a product of prime numbers. Often, in such odd man out questions, most numbers share a combination of small primes like 2, 3, 5 and 7, while one number is either prime itself or built from a very different pattern of primes. We use this method to spot the exceptional number.
Step-by-Step Solution:
Step 1: Factorize 14.14 = 2 * 7, composed of small primes 2 and 7.Step 2: Factorize 27.27 = 3^3, built from the small prime 3.Step 3: Factorize 105.105 = 3 * 5 * 7, again a combination of small primes 3, 5 and 7.Step 4: Factorize 525.525 = 3 * 5^2 * 7, still built from the same small primes 3, 5 and 7.Step 5: Factorize 4993.4993 is a prime number and does not break down into a product of smaller primes like 2, 3, 5 or 7 in simple combinations.
Verification / Alternative check:
We notice that 14, 27, 105 and 525 are all closely related to basic small primes. Three of them explicitly involve 3, 5 and 7 in different combinations, and 27 uses 3 alone. In contrast, 4993 behaves as a large prime number that is not expressible as a product of these small primes in a straightforward way. This strong structural difference in factorization clearly isolates 4993 as the odd one out.
Why Other Options Are Wrong:
27: Although special as a power of 3, it still shares the small prime structure common to 105 and 525.105: Built from 3, 5 and 7, matching the pattern of using small primes.525: Again uses 3, 5 and 7, appearing as a scaled version of 105 with similar prime factors.
Common Pitfalls:
Some learners focus only on the size of the numbers and may be tempted to mark 14 as the odd one because it is smallest, or 4993 because it is largest. However, size alone is not a robust basis for odd man out reasoning. The correct approach is to analyze factorization and see that 4993 stands apart as a large prime while the other numbers are built entirely from small primes 2, 3, 5 and 7.
Final Answer:
The odd number out in the series is 4993.
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