Source: The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.Note that when followed by a fraction, one ordinarily takes a plural verb: One and a half years have passed since I last saw her. The fraction rule has an exception in that amounts are sometimes treated as singular entities: One and a half cups is enough sugar. Note also that the plural rule does not apply to these one-plus-a-fraction constructions that are introduced by the indefinite article. These are always singular: A year and a half has passed since I last saw her.