2
5
1
3
Answer is Wrong!
Answer is Right!
The answer is 3.
The numbers in the sequence are all prime numbers, except for the missing number. The missing number must be a prime number that is not in the sequence. The only prime number that is not in the sequence is 3.
A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number.