To be honest; I played a big gamble there.
Whether every positive even integer can be written as sum and difference of two primes is actually an open problem (till my knowledge goes).
While, the second part can be easily seen. As the sum and difference are odd then there must be one odd and one even prime; and since 2 is the only even prime; the result follows.

## Comments

Sort by:

TopNewestAll even numbers \(\geq 4\); and all odd numbers \(x\) such that \(x-2\) and \(x+2\) both are primes.

(If repetition of primes is allowed)

Log in to reply

Can you please explain how you arrived at the answer.

Log in to reply

To be honest; I played a big gamble there.

Whether every positive even integer can be written as sum and difference of two primes is actually an open problem (till my knowledge goes).

While, the second part can be easily seen. As the sum and difference are odd then there must be one odd and one even prime; and since 2 is the only even prime; the result follows.

Log in to reply