but 1 isn't nt a prime number

Snell is correct.

The number of interest is 29.

A prime number is a number which contains 1 and "itself" as the only factors of the number, where "itself" is a number greater than 1.

For n x (n + 28) to be a prime number, the lower number n has to be 1. This is to fit into the first factor for a prime number.

If n = 1, then n + 28 = 1 + 28 = 29.

This has to be a factor of the number, which is n (n + 28) = 1 (29) = 29

Just to be sure, we have to check that 29 is indeed a prime number. It is not divisible by 2, 3, 4, ... exactly. As such, yes the prime number is 29.

ok thanks a lot:))