five9digitprimefree

Five9digitprimefree is a term used in informal discussions of number theory and algorithm design. It does not refer to a single canonical object; rather, it can denote either a hypothetical property or a short list of nine-digit integers deliberately chosen to avoid primality. In practice, the phrase is used to describe five nine-digit integers none of which is prime, or more broadly a dataset or generator that yields such numbers.

An example of a five-element prime-free set within nine-digit numbers is: 100000002, 100000004, 100000006, 100000008, 100000010. Each is even and greater than 2, hence composite.

Such sets illustrate that within a fixed digit length there can be multiple consecutive non-primes; they can be used to test primality checking, random number generation, and educational demonstrations of prime gaps.

The term is not part of a formal mathematical taxonomy; it appears in problem sets, blogs, and code challenges rather than in peer-reviewed literature.

See also

- Prime gaps

- Composite number

- Primality testing

- Nine-digit numbers

- Problem sets