This is the textcaptchanumeral interface that is called everytime a new instance of Text_CAPTCHA_Numeral is called.
void getAnswer( )
This function will retrieve the answer value from this->answer and return it so we can then display it to the user.
void getFirstNumber( )
This function will get the first number value from $this->firstNumber
void getOperation( )
This function will get the operation string from $this->operation
void getSecondNumber( )
This function will return the second number value