The answer depends on where, within the sequence, the missing number should have been.
The list of numbers that are divisible by 11 is infinite. The first four are: 11,22,33,44 . . .
12. Numbers on a clock face.
The number progression is n+prime numbers progressively increasing starting from 2. The missing number is 29.
It is impossible to list all the prime numbers as there are an infinite number of them. The list of prime numbers starts: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, ... Suppose you could list all the prime numbers and have done so - there is no prime number which is not on the list. Multiply them all together and add 1. This number is not divisible by any of the listed prime numbers as there is always a remainder of 1. So either this new number is a prime number, or there is another prime number not listed which will divide into it. Which means that the list was not all the prime numbers; meaning it is impossible to list all the prime numbers.
19,17,15,13,11,9
The missing number is 5. They're the first five prime numbers.
The list of numbers that are divisible by 11 is infinite. The first four are: 11,22,33,44 . . .
12. Numbers on a clock face.
The number progression is n+prime numbers progressively increasing starting from 2. The missing number is 29.
It is impossible to list all the prime numbers as there are an infinite number of them. The list of prime numbers starts: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, ... Suppose you could list all the prime numbers and have done so - there is no prime number which is not on the list. Multiply them all together and add 1. This number is not divisible by any of the listed prime numbers as there is always a remainder of 1. So either this new number is a prime number, or there is another prime number not listed which will divide into it. Which means that the list was not all the prime numbers; meaning it is impossible to list all the prime numbers.
This list of numbers is the list of prime numbers. Following 11, the next two numbers in the list are 13 and 17.
19,17,15,13,11,9
For a start, you can discard all the even numbers - those that end with 2, 4, 6, 8, 0 - except for the number 2 itself (which in this case, isn't in the list). This only leaves you with the number 11 - which happens to be a prime number.
1
There are an infinite number of prime numbers. It is, therefore, not possible to list those above 50.
2, 3, 5, and 7; also, if it is 1 to 11 inclusive, the list should include 11 because it is a prime number.
Numbers are unique and so the decimal number 11 is 11 and no second number.