Choose a prime number greater than 3.

Multiply it by itself and add 14.

Divide by 12 and write down the remainder.

It will always be 3.

** WHY? **

A prime p has to be 1 or 2 mod 3,

and this implies that p^2 = 1 mod 3.

Also, p has to be 1 or 3 mod 4,

and this implies that p^2 = 1 mod 4.

So, p^2 = 1 mod 12, and so p^2 + 14 = 15 = 3 mod 12