19. A Noun qualified by a Cardinal Numeral does not take an Article. The following exceptions to this rule must, however, be borne in mind : A Noun thus qualified takes the Article when it appears in a Relative Clause ; or when qualified by a Demonstrative Pronoun, or Relative Clause ; or when the Numeral is combined with the Demonstrative Pronoun (see the list at the foot of page 573) ; or when that particular Number is specially definite ; or after kwa, how many; or in quoting some well-known instance or case in point. Where the Noun forms part of a clause in which the Verb is preceded by una, wau, vava, ova, ovo, yavana, kufwila owu...ko, it takes the Article, since it is always definite.