11
13
9
15
Answer is Right!
Answer is Wrong!
The missing number is 13.
The numbers in the sequence are all prime numbers, except for 10, which is a composite number. The sequence starts with 2, which is the smallest prime number, and then increases by 2 each time. Therefore, the missing number must be the next prime number after 11, which is 13.
A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. A composite number is a natural number greater than 1 that is not prime.