Measure by displacement. When a mass enters a body of liquid, a volume of liquid equal to the volume of the mass entering the water is displaced. It’s called archemedies principle iirc, from there take the density of the mass to figure out the weight

This is essentially saying the set of real numbers have the same amount of numbers as the set of natural numbers, which is untrue. Take any random number from a list of numbers between 0 and 1, for instance 0.7362957293749274. Now add 1 to each number and if it’s a 9 roll it back to an 8. The number is now 0.84738683858385. This number will not be anywhere in your list.