Explanation:
It is known that 1 gram contains 1000 milligrams. And, mathematically we can represent it as follows.
[tex]\frac{1 g}{1000 mg}[/tex] or [tex]\frac{1000 mg}{1 g}[/tex]
So, when we have to convert grams into milligrams then we simply multiply the digit with 1000. And, if we have to convert a digit from milligrams to grams then we simply divide it by 1000.