Why is there 1000mg in a gram but on charts the prefix milli represents 0.001

Question

When I was looking at a conversion factor everything was looking good until I had to covert mg to grams...is showed 1000 milligrams to 1 gram but yet on charta it's known to be 0.001 grams so why is It 1000

Answer 1

1000 mg = 1g

 

Therefore, 

 

1 mg = (1/1000) g = 0.001 g

 

If you have grams, multiply by 1000 to get mg.  But if you have mg, divide by 1000 to get g.  Dividing by 1000 is the same as multiplying by 0.001.