High Quality Content by WIKIPEDIA articles! In non-standard analysis, the standard part function "st" is the key ingredient in Abraham Robinson's resolution of the paradox of Leibniz's definition of the derivative as the ratio of two infinitesimals. The standard part of any infinitesimal is 0. Thus if N is a hypernatural, then N is infinitesimal, and st =0. The existence of the standard part function is a consequence of the completeness of the reals or the fact that finite closed intervals of the reals are compact. The standard part function "st" is not an internal object.