Pennyweight is derived from the price for a hundred nails in 15th century England: the larger the nail, the higher the cost per hundred. The pennyweight also bears no relation to the weight of the American "penny" (1 cent) coin, which weighs 2.5 g (for those minted after 1982). Pennyweight A pennyweight (abbreviated dwt, from denarius weight) is a unit of mass that is equal to 24 grains, of a troy ounce, of a troy pound, approximately 0.054857 avoirdupois ounce and exactly 1.55517384 grams. In the Middle Ages, a British penny's weight was literally, as well as monetarily, of an ounce
Post-harvest losses (grains) of edible from less-desired products is always difficult to achieve but, even so, there are significant differences in milling efficiency. In the case of rice, milling outturns can vary from 60% or less to around 67%, depending on the efficiency of the mill. Even a 1% increase in yield of whole grain rice can thus result in huge increases in national food resources. Grains are produced on a seasonal basis. In many places there is only one harvest a year. Thus most production of maize, wheat, rice, sorghum, millet, etc. must be held in storage for periods varying from a