Middle Earth numerals - more like Roman?

[Gordis]

I have suddenly found out that I know very little about ME numerals. We have detailed accounts of different writing systems, but next to nothing (as far as I know) is told about the rendition of numbers.

The quote I can think of is this
On the flat under-side [of the stone] Frodo saw some scratches: I"III 'There seems to be a stroke, a dot, and three more strokes,' he said.
'The stroke on the left might be a G-rune with thin branches,' said Strider. 'It might be a sign left by Gandalf, though one cannot be sure. The scratches are fine, and they certainly look fresh. But the marks might mean something quite different, and have nothing to do with us. Rangers use runes, and they come here sometimes.'
'What could they mean, even if Gandalf made them?' asked Merry
'I should say,' answered Strider, 'that they stood for G3, and were a sign that Gandalf was here on October the third: that is three days ago now. It would also show that he was in a hurry and danger was at hand, so that he had no time or did not dare to write anything longer or plainer. If that is so, we must be wary.'- the Knife in the Dark.

So if 3 was rendered as III, the ME numerals likely were close to Roman ones.
But maybe there are some more data out there somewhere?

[Earniel]

Interesting thought, Gordis. I never considered the numerals. I don't recall any writings about Middle-earth counting systems, but I have not read many of the HoME-books. If there is an essay on numerals in Middle-earth, I suppose somewhere in HoME is your best shot.

[Valandil]

I don't think this is necessarily indicated. I think Strider had to sort of interpret what those three strokes meant - and concluded that the one leaving them (presumably Gandalf) had meant them to represent the number '3'. But I don't think the common symbol for '3' was used, or there would have been no guessing about it. And... I think it was intended to be a discreet message, a little coded.

I wonder if the Nazgul could read something that was written there, in this manner. Poor eyesight and all. Of course - they already knew Gandalf was there on October 3rd. So... who was Gandalf trying to hide the message from anyway? ;) (will anyone suggest Gildor? :p )