> You measure the wall with a ruler and get 7 feet, then you measure the couch and get 7 feet. Can you fit the couch against that wall?

Normally, yes: the couches generally have somewhat squishy... stuffing? filling?.. which hang off the wooden frame, so you generally can squeeze a couch from the sides a bit to fit it into slightly narrower space.

> say 1/10th of a foot.

This is unholy. Either say "an inch" for this hypothetical scenario, or use some decimal-based measurement system.