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December 10th, 2010, 05:24 AM   #1
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Roman counting system

The basis of the Roman numerical system is counting on the fingers indicates that the Latin word "Jigitus" where we use word is derived from "digit" .Romans wrote numbers from one to four as follows



the symbol which represent five is v
may represent the gap between the thumb and the rest of the fingers



In order to avoid writing number 4 ( iiii) ,they used the place value for symbol ,so if was written to the left of the symbol another symbol bigger than it means the Sum of the two numbers and is was written to the right of the symbol another symbol bigger than it means difference between the two numbers .numbers 6 , 7 , 8 are



To write 10 they used symbol X , so by using the former rule 9 = IX , 11 = XI , 12= XII , 13= XIII , 14= XVI , 15 = XV , 16 = XVI , 17 = XVII , 18= XVIII , 19 = XIX , 20= XX and 30 = XXX

In order to avoid writing number 40 = XXXX they used L to represent 50 so 40 = XL , 60 = LX and so on. To write 100 they used symbol C ,so 90 = XC , 120 = CXX ,150= CL and 200 = CC. To write 500 they used D ,so CD = 400 , DC = 600 and 700 = DCC . They used M to write 1000 ,so 900 = CM , 1100 = MC and 1300 = MCCC.
now to write 1408 by using Roman counting system = MXDVIII
To write 1564 = MDLXIV
To write 2010= MMX.
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December 10th, 2010, 06:31 AM   #2
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Re: Roman counting system

Quote:
Originally Posted by mrhesham
The basis of the Roman numerical system is counting on the fingers indicates that the Latin word "Jigitus" where we use word is derived from "digit" .
Surely that is digitus, 'finger'? iigitus (which may be written jigitus or IIGITVS) isn't a Latin word I know or can find readily.

Quote:
Originally Posted by mrhesham
the symbol which represent five is v
may represent the gap between the thumb and the rest of the fingers?
That has been theorized, but it's more likely that it derives from a tally mark. You'd write numbers
|
||
|||
||||
||||/
||||/|
||||/||
||||/|||
||||/||||
||||/||||X
where the different marks help you count when the numbers get large.

Quote:
Originally Posted by mrhesham
In order to avoid writing number 4 ( iiii) ,they used the place value for symbol ,so if was written to the left of the symbol another symbol bigger than it means the Sum of the two numbers and is was written to the right of the symbol another symbol bigger than it means difference between the two numbers .
Yes, exactly as you say. This was a late invention, though -- it was first used, as I recall, in medieval Europe after the fall of the western Roman Empire.

Worth noting -- though you surely know -- you can only subtract the next smaller tens place. VX and IC aren't allowed.

Quote:
Originally Posted by mrhesham
In order to avoid writing number 40 = XXXX they used L to represent 50 so 40 = XL , 60 = LX and so on. To write 100 they used symbol C ,so 90 = XC , 120 = CXX ,150= CL and 200 = CC. To write 500 they used D ,so CD = 400 , DC = 600 and 700 = DCC . They used M to write 1000 ,so 900 = CM , 1100 = MC and 1300 = MCCC.
now to write 1408 by using Roman counting system = MXDVIII
The symbols for thousands and above changed over time; the earlier version was more like ? or C|?.
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