It is impossible for something to weigh 200 grams. A gram is a unit of mass, while weight is a measure of force. However, a penny has a mass of roughly 2.5 grams, so 80 pennies would give you a mass of 200 grams, or a weight of 0.44 pounds.
Mass details the amount of matter in a substance. Weight is the force exerted by objects with mass while under the pull of gravity. Mass and force use the kilogram and the Newton for standard units, respectively. The equation to find the amount of force exerted by an object is F = ma, where F is the force applied, m is the mass of the object in question, and a is the acceleration of the object in question. The conversion factor to find the mass of an object given its weight on earth, or the weight of an object given its mass, is 1 pound = 453.592 grams.
Weight changes depending on location. For instance, a 200 pound man on Earth would weigh 76 pounds on Mars. Mass on the other hand, does not change. So that same man that weighs 200 pounds on Earth and 76 pounds on Mars would have a mass of roughly 90,718 grams, given that 1 pound of force on Earth is equal to 453.592 grams.