A full box of paperclips weighs 150 grams. people use some paperclips from the box, and it now weighs 138 grams. how many milligrams lighter is the box?

Here is the answer. Since the given values are in the "gram" units, and the question is asking if how many grams lighter is the box, what we are going to do is just to convert the units so that it would be the same. So 150 grams minus 138 grams is 12 grams. So it is 12 grams lighter, and 12 grams is equivalent to 12,000 milligrams. Hope this answers your question.