What is the name of the device that the Romans used for calculations?

Probably an abacus.

Please people, the Babaloyians and Chinese invented the Abacus. But, the Romand did steal the idea.

According to Wikipedia: http://en.wikipedia.org/wiki/Abacus

"The first abacus was almost certainly based on a flat stone covered with sand or dust. Words and letters were drawn in the sand; eventually numbers were added and pebbles used to aid calculations. The Babylonians used this dust abacus as early as 2400 BC. The origin of the counter abacus with strings is obscure, but India, Mesopotamia or Egypt are seen as probable points of origin. China played an essential part in the development and evolution of the abacus."

According to Wikipedia: http://en.wikipedia.org/wiki/Roman_Numerals

"Roman numerals are a numeral system originating in ancient Rome, adapted from Etruscan numerals. The system used in classical antiquity was slightly modified in the Middle Ages to produce the system we use today. It is based on certain letters which are given values as numerals.

Roman numerals are commonly used today in numbered lists (in outline format), clockfaces, pages preceding the main body of a book, chord triads in music analysis, the numbering of movie publication dates, successive political leaders or children with identical names, and the numbering of some sport events, such as the Olympic Games or the Super Bowl.

For arithmetics involving Roman numerals, see Roman arithmetic and Roman abacus."

According to Wikipedia: http://en.wikipedia.org/wiki/Roman_abacus

"The Romans developed the Roman hand abacus, a portable, but less capable, base-10 version of the previous Babylonian abacus. It was the first portable calculating device for engineers, merchants and presumably tax collectors. It greatly reduced the time needed to perform the basic operations of Roman arithmetic using Roman numerals."

Roman numerals are hard to work with though because they are not organized like the Arabic number system that the world uses today. At every 5, 50, and 100 intervals there is a new character required.

There was a Roman Numeral abacus. see below:

Well...I thought the Greeks used the abacus...so either that or whatever came between that and the slide rule. lol.

nice question

if you don't mind, I will make this as my recording so that I have the copy of your question.

I know only of the early surveying instruments . . like circumferentor, . . levella, . . but no device for calculation

I will be watching this

thanks