(1x10^3 kg/in^3) x (2x10^2in^3/gallon) = 2x^5 kg/gallon.

Can this be right?
Thanks for the help!

2. I think you meant $\frac{2 \times 10^{5} \mbox{kg}}{\mbox{gallon}}$. And yes that's correct. You just cancel the units accordingly.

I get it now. Thank you very much!
Jerry