I don't have dyscalculia but behind the numbers I have my own intuitive system(s) that I jump to sometimes when doing arithmetic. I think we all do since the early days arithmetic in school or what not, perhaps the dyscalculia folk missed making some connection at some point. I feel that arithmetic with numbers without that intuitive system is rote memory..

Indeed, I do also have an intuitive system for this; that's what I mean by "make up a quantity". When something makes up a quantity for me, then I can perform math on it. I have to wonder if my friend with dyscalculia doesn't have a "quantity" system like I do. They can't really perform multiplication or division but can technically perform basic addition and subtraction, though it takes them a while. I think it may be the rote memory you mention doing that for them.