The result of your conversion between pound/cubic mile and grain/gallon [US] appears here
To convert between Pound/cubic Mile and Grain/gallon [US] you have to do the following:
First divide 0.45359237/(((0.0037854118/231)*1728*27)*5451776000) / ((0.45359237/16)*(192/175)/480)/0.0037854118 = 0.00000001
Then multiply the amount of Pound/cubic Mile you want to convert to Grain/gallon [US], use the chart below to guide you.
Symbol: lb/mi³
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Symbol: gr/gal
No description