Convert from pound to grain

Unit Definition (pound)
The pound is a traditional unit of mass or weight. The Romans used a pound (the libra pondo, "pound of weight") divided into 12 ounces. All the countries of western Europe used similar units, divided into 12 or 16 ounces, until the advent of the metric system. 12-ounce pounds were common in Italy and southern France, but in Spain and northern Europe 16-ounce pounds became the norm. The word libra is used for this unit in Italy, Spain, and Portugal; in France it is called the livre. Further north, the Latin word pondo ("weight") is the origin of the names of the English pound, Dutch pond, Danish pund, German pfund, and Russian funt. In England, two different "pound" units became standard. The unit now in general use in the United States is the avoirdupois pound, so-called from a French phrase avoir du poids, literally "goods of weight," indicating simply that the goods were being sold by weight rather than by volume or by the piece. The avoirdupois pound is divided into 16 ounces. By international agreement, one avoirdupois pound is equal to exactly 453.592 37 grams; this is exactly 175/144 = 1.215 28 troy pounds.

Unit Definition (grain)
The grain is a traditional unit of weight. The grain, equal to 1/480 troy ounce, or exactly 64.798 91 milligrams, was the legal foundation of traditional English weight systems, with various pounds being defined as a specified number of grains: 5760 grains in a troy pound and 7000 grains in an avoirdupois pound, for example. In the version of the troy system used by jewelers, there are 24 grains in a pennyweight and 20 pennyweight in an ounce. In the version used by apothecaries, there are 20 grains in a scruple, 3 scruples in a dram, and 8 drams in an ounce. Originally the grain was defined in England as the weight of a barleycorn. This made the English grain larger the corresponding grain units of France and other nations of the Continent, because those units were based on the weight of the smaller wheat grain.