It is my understanding that there are no decimals or fractions in Roman Numerals.
Another Answer:-
The Roman numeral system once used fractions to a limited extent and the fractional numeral for 1/2 or 0.5 was S thus facilitating the correct calculations of the above numbers into Roman numerals as follows:-
VIIIS+XVIIIS = XXVII => 8.5+18.5 = 27
SIX+SIXX = XXVII => (10-1.5)+(20-1.5) = 27
VIIIS+SIXX = XXVII => 8.5+(20-1.5) = 27
SIX+XVIIIS = XXVII => (8-1.5)+18.5 = 27
XVIIIS-VIIIS = X => 18.5-8.5 = 10
SIXX-SIX = X => (20-1.5)-(10-1.5) = 10
SIXX-VIIIS = X => (20-1.5)-8.5 = 10
XVIIIS-SIX = X => 18.5-(10-1.5) = 10
Note that in mathematics -(10-1.5) becomes 1.5-10 and in the book '50 mathematical ideas you really need to know' by Tony Crilly he points out the fact that the ancient Romans would sometimes use SIX instead of VIIIS which both are the equivalent of 8.5.
QED
See answer to question: ' How do you add together 1666 and 1999 in two different ways using Roman numerals'
Roman numerals are entirely inappropriate for doing such calculations. I believe the people in Roman times did such calculations on an abacus or something similar - which is basically similar to converting them to the Arabic numbers we use. If you really want to do it in Roman numerals - which is basically NOT a good idea - you would have to keep the thousands, hundreds, etc. separate, and handle carry (for addition) and borrowing (for subtraction).
According to my calculations,mccxxix in Hindu Arabic numerals is 1229
The Romans did their calculations on an abacus counting device which was the equivalent to a primitive calculator.
When 9 is converted into Roman numerals it is IX which is an abridged version of VIIII and so the required calculations are as follows:-MDCCLXXVI+IX = MDCCLXXXV => 1776+(10-1) = 1785MDCCLXXVI+VIIII = MDCCLXXXV => 1776+9 = 1785MDCCLXXVI-IX = MDCCLXVII => 1776-(10-1) = 1767MDCCLXXVI-VIIII = MDCCLXVII => 1776-9 = 1767Note that in mathematics -(10-1) changes to 1-10QED
See answer to question: ' How do you add together 1666 and 1999 in two different ways using Roman numerals'
Roman numerals are entirely inappropriate for doing such calculations. I believe the people in Roman times did such calculations on an abacus or something similar - which is basically similar to converting them to the Arabic numbers we use. If you really want to do it in Roman numerals - which is basically NOT a good idea - you would have to keep the thousands, hundreds, etc. separate, and handle carry (for addition) and borrowing (for subtraction).
Numerals are used for mathematical calculations. Mathematical calculations are used in science. This is the way Roman numerals related to Roman science.
According to my calculations,mccxxix in Hindu Arabic numerals is 1229
The Romans did their calculations on an abacus counting device which was the equivalent to a primitive calculator.
Not withstanding today's modern notation of Roman numerals in as much that the ancient Romans would have probably worked out the required calculations as follows: MDCCLXXVI+IC = MDCCCLXXV => 1776+(100-1) = 1875 MDCCLXXVI+LXXXXVIIII = MDCCCLXXV => 1776+99 = 1875 MDCCLXXVI-IC = MDCLXXVII => 1776-(100-1) = 1677 MDCCLXXVI-LXXXXVIIII = MDCLXXVII => 1776-99 = 1677
When 9 is converted into Roman numerals it is IX which is an abridged version of VIIII and so the required calculations are as follows:-MDCCLXXVI+IX = MDCCLXXXV => 1776+(10-1) = 1785MDCCLXXVI+VIIII = MDCCLXXXV => 1776+9 = 1785MDCCLXXVI-IX = MDCCLXVII => 1776-(10-1) = 1767MDCCLXXVI-VIIII = MDCCLXVII => 1776-9 = 1767Note that in mathematics -(10-1) changes to 1-10QED
Doing arithmetic with Roman numerals is exasperating, and imho a pointless waste of time, except to demonstrate the obvious superiority of our "normal numbers," which use base-10 radix / positional notation that includes a zero digit as a placeholder. I'd venture to say science & technology -- commerce, too -- could never have developed in recent centuries if we still used Roman numerals for calculations. However, this web site explains some methods: http://turner.faculty.swau.edu/mathematics/materialslibrary/roman/
In todays modern configuration of Roman numerals 49 is now considered to be XLIX but the ancient Romans would have probably added the given numbers in either of the following formats:-A: MDCCLXXVI+IL = MDCCCXXV => 1776+(50-1) = 1825.B: MDCCLXXVI+XXXXVIIII = MDCCCXXV => 1776+49 = 1825.For more complicated calculations the Romans would have used an abacus calculating device.QED
Nowadays 999 when converted into Roman numerals is now considered to be CMXCIX which does not quite easily lend itself for the purpose of arithmetical operations but the ancient Romans would have probably worked out the given three calculations as follows:-IM+DCCLXXVII = MDCCLXXVI => (1000-1)+777 = 1776DCCCCLXXXXVIIII+DCCLXXVII = MDCCLXXVI => 999+777 = 1776DCCCCLXXXXVIIII-DCCLXXVII = CCXXII => 999-777 = 222QED
The requested calculations are as follows:- MDCCLXXVI+IM = MMDCCLXXV MDCCLXXVI+DCCCCLXXXXVIIII = MMDCCLXXV MDCCLXXVI-IM = DCCLXXVII MDCCLXXVI-DCCCCLXXXXVIIII = DCCLXXVII
The modern way of expressing 19 into Roman numerals is now XIX but the ancient Romans would have probably worked out the above calculations as follows: A: XXXI+IXX = L => 31+(20-1) = 50. B: XXXI+XVIIII = L => 31+19 = 50. C: XXXI-IXX = XII => 31-(20-1) = 12. D: XXXI-XVIIII = XII => 31-19 = 12.