weight dosing bimectin so I can do the maths right

If I have understood this right when it comes to weight dosing for Bimectin, a MCG (microgram) is 10 to the -6 which means 6 places to the right of the decimal point? (0.000001) which means that 500 MCG per kilogram of bodyweight would equal 0.0005 gram being 1/2 of a milligram . Therefore each milligram 0.001 of a gram = 2 KG of body weight? Is that correct Tweet