But what about Thorin, Fili, Kili, Dwalin, Ori, Nori, Dori, Gloin, Oin, Bifur, Bofur, and Bombur?

I would tend to agree that it’s likely an aspect of the reasoning for the double circle; a visual pun. I don’t know enough to dispute the Wikipedia article with evidence, however.

If that is the reasoning, I wish they would’ve done something less ambiguous, like -/c or over-lined 100.

Um actually…

Latin: per centum

Italian per cento

Abbreviated to p. cento

Then just pc with a loop for the o in cento

Then the fraction bar came around to sub for per, the c became a circle, and % was born.

(Most of this after the adoption of Arabic numerals)