How can convert pound per pound to grains per pound?

You need to divide the price per pound by the price per kilogram.(Price per pound)/(Price per kilogram) = Kilograms per poundAlternatively, I could just tell you that 1 pound = 0.45359237 kilograms

You multiply your pounds per day by seven to get your answer if you lost the same amount of pounds each day.

Find the reciprocal

This question cannot be answered sensibly. A pound per square inch is a measure of pressure, with dimensions [ML-2]. A pound is a measure of mass, with dimensions [M]. The two measure different...

Those units measure different things, so you really can't convert one to the other.