Directions: Insert the missing number: 11, 13, 17, 19, 23, 29, 31, 37, 41, (.....)

### Concept & Logic The sequence is a straightforward list of consecutive prime numbers starting from 11. ### Step-by-Step Solution Let's evaluate the numbers: - 11 (Prime) - 13 (Prime) - 17 (Prime) - 19 (Prime) - 23 (Prime) - 29 (Prime) - 31 (Prime) - 37 (Prime) - 41 (Prime) These are all positive integers greater than 1 that have no positive divisors other than 1 and themselves. The sequence asks for the immediate next prime number after 41. - 42 is even (divisible by 2). - 43 is only divisible by 1 and 43. Thus, it is prime. ### Exam Strategy & Shortcut Prime number series are extremely common. If differences don't yield a clear pattern (here: 2, 4, 2, 4, 6, 2, 6, 4 - no simple pattern), immediately check for prime or composite properties. ### Common Pitfall Choosing 47 (the prime after 43) by skipping a term, or selecting 51 thinking it's prime (it's $17 \times 3$). ### Final Answer Therefore, the correct answer is **43**.