Mo. Rev. Stat. § 413.165

A representation or an advertisement for the sale of a commodity by weight, measure or count, whether packaged or unpackaged, which states the retail price, shall also contain a clear and conspicuous declaration of the quantity in terms of weight, measure or count, to include any size or dimension designation. Where a dual declaration is required, only the declaration that sets forth the quantity in terms of the largest whole unit with any remainder expressed in fractions of weight or measure required by law or regulation to appear on the package need appear in the advertisement.