What subtleties? What is incorrect? 

Can someone explain the subtleties that have eluded me, and be specific about the errors I introduced per the the summary in this undoing please? As far as I know: 1 imperial pint does equal 20 imperial fluid ounce, 1 US pint does equal to 16 US fluid ounces and the imperial fluid ounce is about 5% smaller than the US fluid ounce.