In metric, one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade—which is 1 percent of the difference between its freezing point and its boiling point. An amount of hydrogen weighing the same amount has exactly one mole of atoms in it. Whereas in the American system, the answer to ‘How much energy does it take to boil a room-temperature gallon of water?’ is ‘Go fuck yourself,’ because you can’t directly relate any of those quantities.
You should never bother trying to remember where you put something. You should just imagine needing to put it somewhere now, then go to the place you pick. Because why would you pick a different location now than you did earlier? Your personality is more stable than that. It's not like we wake up each day as different people. It's just that we don't trust ourselves.