Comment by jmull

Hopefully most people get that the exact meaning of "pixel" depends on context?

It certainly doesn't make sense to mix different meanings in a mathematical sense.

E.g., when referring to a width in pixels, the unit is pixel widths. We shorten it and just say pixels because it's awkward and redundant to say something like "the screen has a width of 1280 pixel widths", and the meaning is clear to the great majority of readers.