> I am not sure why 0 is not considered a prime number in this context. So, if you have a set with multiplication and addition, that is called a ring. A very n

> I am not sure why 0 is not considered a prime number in this context. So, if you have a set with multiplication and addition, that is called a ring. A very nice class of rings is called fields. This is where division is possible. Another way to state that 'division is possible' is to say that multiplication is a group operator on the entire set except zero.