Final answer:
1 gram is equal to 1000 milligrams, therefore the blank in the equation '1 g = _______ mg' should be filled with the number 1000.
Step-by-step explanation:
The blank in the equation '1 g = _______ mg' can be filled with the number 1000. This is because 'g' stands for gram, and 'mg' stands for milligram. There are 1000 milligrams in a gram, so the equation can also be expressed as '1 g = 1000 mg'.
Learn more about Metric Conversion