Does greater than mean addition

Answer 1

Only indirectly because the value added to the quoted number is not stated.

Thus 20 > 15 and 102 >100; but in neither case are we quoting the 5 and 2 added to 15 and 100.

So we can give a range whose lower limit is the value after the "greater than" sign, and the upper limit is at least suggested or understood by context.

E.g. "Most adult humans are >5ft tall".

But we also know humans <7ft tall are extremely rare.

"Most astronomical objects are >10 light years from Earth".

Well, there are two stars and the rest of the Solar System within that limit, one obviously being the Sun, at about 4.5 light-minutes, but the distances to almost everything else stretches beyond that observable, into infinity as far as anyone can tell!