Difficulty: Easy
Correct Answer: 17
Explanation:
Introduction / Context:
This checks recognition of prime numbers and accurate addition. Primes are integers greater than 1 with exactly two distinct positive divisors: 1 and the number itself. Listing the earliest primes and adding them carefully produces the correct sum quickly.
Given Data / Assumptions:
Concept / Approach:
Identify the primes: 2, 3, 5, 7 are the smallest four primes. Then add them explicitly. Writing the list prevents the common error of including 1 or skipping 7 by mistake. Ensuring fundamental definitions avoids traps in multiple-choice settings.
Step-by-Step Solution:
List primes: 2, 3, 5, 7.Add: 2 + 3 = 5.Add next: 5 + 5 = 10.Add last: 10 + 7 = 17.
Verification / Alternative check:
Double-check primality: each of 2, 3, 5, 7 has no positive divisors other than 1 and itself. Re-sum quickly to confirm 17.
Why Other Options Are Wrong:
Common Pitfalls:
Counting 1 as a prime; forgetting that 2 is prime; adding too fast and arriving at 16 instead of 17.
Final Answer:
17
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