@abc.abstractmethod<EOL><INDENT>def get_lowest_numeric_score(self):<DEDENT>
return<EOL>
Gets the lowest number in a numeric grading system.

        :return: the lowest number
        :rtype: ``decimal``
        :raise: ``IllegalState`` -- ``is_based_on_grades()`` is ``true``

        *compliance: mandatory -- This method must be implemented.*