Question

The sum of three different numbers is 18. lf every number is a prime number, what are the three numbers?

Answer 1

`(2,3,13)` and `(2,5,11)`

Explanation:

The sum of three odd numbers is always odd. Thus, `18` cannot be the sum of three odd primes.

In other words, one of the numbers must be `2`, the only even prime.

Now, we just need to find two primes that sum up to `16`.

The only prime numbers we can use are: `3,5,7,11,13`

By trial and error, `3+13` and `5+11` both work.

Therefore, there are two possible answers: `(2,3,13)` and `(2,5,11)`.