This question cannot be answered sensibly. A millilitre is a measure of volume, with dimensions [L3]. A gram is a measure of mass, with dimensions [M]. Basic dimensional analysis teaches that you cannot convert between measures with different dimensions such as these without additional information.
It takes only a little mental effort to compare a ml of air and a ml of water to see that the two will have very different masses.
It's actually the other way around!! There is 1000 millograms in a gram.
That is 0.3 of a gram
There are 1000 milligrams to one pound
0.45
2,000mg
Three grams would be equal to 3000 milligrams. One gram would equal 1000 milligrams. The metric prefix of 'milli' represents a factor of one thousandth.
25
500 milligrams is equal to .5 grams.
3000
One gram is equal to about 980.665 dynes.
1,000
200 mg