This answer is not correct. 

You probably inverted the conversion factor 1000mg/g thereby dividing instead of multiplying by 1000. Another common error is to try to make the conversion in one step by figuring out a conversion from decigrams to milligrams directly. You will make far fewer errors if you do these step by step using the definitions of the prefixes used. Most people also make fewer errors if they use whole numbers; 1000mg/g rather than mg/0.001g.