# Is every natural number a prefix of a prime number? [duplicate]

Let n be the representation of a natural number in a non-unary base. Is it a prefix of the representation of a prime number over the same base?

For example: in decimal, the answer for 10 is yes, because 103 is prime. Is this true for every number?

EDIT: As Henning Makholm has pointed out, this question has been asked before: Proof that there are infinitely many prime numbers starting with a given digit string

• Not only is there always such a prime -- there are infinitely many, as demonstrated in the question Proof that there are infinitely many prime numbers starting with a given digit string Jun 8, 2012 at 16:17
• I think your question is more complicated than it looks like. For instance, if you work in base $7$, the number $7$ is written $10$, so you're looking for a number of the form $10****$ in base $7$ that is prime. Jun 8, 2012 at 16:18
• Thank you, that was exactly what I was looking for. Jun 8, 2012 at 16:43