The result of your conversion between gram/cubic kilometer and grain/gallon [US] appears here
To convert between Gram/cubic Kilometer and Grain/gallon [US] you have to do the following:
First divide 0.001/1.0E+9 / ((0.45359237/16)*(192/175)/480)/0.0037854118 = 0.
Then multiply the amount of Gram/cubic Kilometer you want to convert to Grain/gallon [US], use the chart below to guide you.
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