What makes a number prime or composite?

Question

What makes a number prime or composite?

Answer 1

Take a positive integer and try dividing it by another positive integer. If it can be divided by another positive integer (other than 1 or itself) then it is composite. You can think of it be "composed" of other integers. If it can't be divided by any other integers (except 1 and itself), then the number is prime. There is an exception for the number 1 which isn't considered prime or composite.



List of prime numbers:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, ...



List of composite numbers:

4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25, 26, 27, ...

Answer 2

A number that is prime or composite is a number that is :

- a positive integer

- not equal to 1



Those are the two criteria that makes a number prime or composite. If a number doesn't satisfy those two criteria, then the number is not prime nor composite.

Answer 3

A number is Prime if its factors are only 1 and itself.

A number is composite, if it's not prime.



And as Puzzling stated, 0 or 1 are neither prime nor composite. You have to have at least two factors to be identified as one or the other.