To convert $1200$ milligrams to grams, you divide by $1000$, which gives you $1.2$ grams.

Let’s delve deeper into the conversion from milligrams to grams and the underlying principles. The metric system, employed in most countries around the world, is structured around powers of ten, simplifying the process of unit conversion. In this system, $1$ gram (g) is equivalent to $1000$ milligrams (mg).

To convert milligrams to grams, the formula is straightforward: you divide the number of milligrams by $1000$. This division is necessary because each gram contains $1000$ milligrams. For instance, if you have $1200$ milligrams and wish to express this quantity in grams, you would carry out the following calculation:

Thus, $1200$ milligrams is equal to $1.2$ grams. This conversion method is applicable to any instance where you need to switch between milligrams and grams. Just remember this essential guideline: to convert from milligrams to grams, divide by $1000$; conversely, to convert from grams to milligrams, multiply by $1000$. This simple rule will enable you to perform these conversions with confidence and ease.