Many people have heard YouTube – 0.002dollar = 0.002cent.
It seems to me that there are a few things to be explained.
First, why, although they can recognize that units of measurement are important when dealing with integers and with some easy fractions (I’m not sure where easy leaves off), at some point they see the 0.002 but can’t see the units anymore.
Second, why they cannot be led through a series of steps to see the difference.
Third, why they think that a difference concerning arithmetic is a matter of opinion, by which they mean a mere matter of opinion, in which no opinion is right and no opinion is wrong — in fact, no opinion is even better than another.
Fourth, why they can write off the attempt to get them to see the difference by glibly saying, “I’m not a mathematician” — as though (a) simple arithmetic were higher mathematics, and (b) not being a mathematician were a point of pride.