Mo. Rev. Stat. § 413.215: Weighing or measuring device in business place rebuttable, presumption of use for business.

Whenever there shall exist a weight or measure or weighing or measuring device in or about any place in which or from which buying or selling is commonly carried on, there shall be a rebuttable presumption that such weight or measure, or weighing or measuring device, is regularly used for the business purposes of that place.