Cube (algebra) however, easy to show that most numbers are not perfect cubes because "all" perfect cubes must have digital root 1, 8 or 9. That is their values modulo 9 may be only −1, 1 and 0. Moreover, the digital root of any number's cube can be determined by the remainder the number gives when divided by 3: Every positive integer can be written as the sum of nine (or fewer) positive cubes. This upper limit of nine cubes cannot be reduced because, for example, 23 cannot be written as the sum of fewer than nine positive cubes: The equation has
The Cube Root of Uncertainty The Cube Root of Uncertainty The Cube Root of Uncertainty is a collection of science fiction short stories by American writer Robert Silverberg, published in hardcover by Macmillan in 1970 and issued in paperback by Collier Books in 1971. No further editions have been issued. "Passengers" won the Nebula Award for Best Short Story and was nominated for the Hugo Award. Joanna Russ gave the collection a mixed review, noting its division between early work ("Old Silverberg is an idiot") and more recent efforts ("New Silverberg is something else: a highly colored, gloomy, melodramatic, morally allegorical writer who luxuriates in