Abacus

[Sutoris]

So how was the counting done on one of these?

I don't know Dem, I just made it :roll:

[agrimensor]

looks very good sutorius, now just ad the beads.

[jvrjenivs]

So how was the counting done on one of these?

It's quite easy. You start with the lane where the I is the sign. Every 'rivet' on the lower part has value 1, the upper one has value 5. So, start with all down, and put one up will make 1. Two up will make 2, etc. After 4 your lower rivets are all gone, so the upper should now take over, and all lower are back to zero. Now you have 5 and can go to 9.
For 10, go to the lane with the X and on the lower part every rivets is worth 10. Etc, etc.

Hope this makes it more clear.

[M. Demetrius]

BTW, Sutoris, that is hardly "crude". Excellent metalwork.

Thanks J, that's what I'd thought, but some of the symbols were unfamiliar to me.

[Sutoris]

Thank Dem and Agri!
The beads are Jef's problem

Jvrjenivs,
what about the lanes on the right of the lane with the I :?

[jvrjenivs]

Well, those got me puzzled this morning, so I didn't comment on them If I remember correctly they can be used to calculate even smaller values as 'one'. But I've to look that up, as my memory doesn't serve me at the moment as for their exact use/function...

[Marcus Mummius]

Hi Robert,

The ivory one looks nice, but is it an authentic Roman one?

I didn't know the romans used this kind of notations...

For example:

XM= 10000
CM= 100000
MM= 1000000