you know the old trick question, "which is heavier, a hundred pounds of feathers or a hundred pounds of bricks"?
a neat variant is to ask between feathers or gold, because people will say they're the same but they actually aren't: the hundred pounds of feathers are heavier because gold is measured in (lighter) troy pounds
And it's the opposite for ounces, because there are enough fewer Troy ounces in that scale's pound. Historically, there were even more competing measurement systems before the Avoirdupois pound took over common usage because of the number of times it could be subdivided by two.
@Tathar twelve is better though because you can divide it by three too
Maybe that's why it didn't get abandoned alongside the other systems?
In related trick questions, the avoirdupois pound is currently defined as a unit of mass in grams, not weight. The weight unit is pound-force. So even though you don't weigh the same on the moon, you are the same number of pounds there.
@Tathar interestingly though in scientific and engineering work, in the rare case that pounds are used, it tends to be assumed that lb means pounds-force, while lbm is used for pounds-mass
And yet in those fields, because of the precision needed, the variation in Earth's gravitational force is more likely to cause problems.
This is the sort of thing that leads teachers and professors to stress how important it is to be sure of your units. Bad things happen when we don't make sure we're using the right units.
