Nowadays we would express 19 in Roman numerals as XIX but in ancient Rome the equivalent of 19 was XVIIII or IXX thus facilitating the speed and ease of addition in either of the following formats:-
IXX+LXII = LXXXI => (20-1)+62 = 81
LXXXI+IXX = C => 81+(20-1) = 100
Alternatively:-
XVIIII+LXII = LXXXI => 19+62 = 81
LXXXI+XVIIII = C => 81+19 = 100
Note that the Latin word for XVIIII is novemdecim and and for IXX it is undeviginti but there is no Latin word for todays notation of 19 as XIX
See answer to question: ' How do you add together 1666 and 1999 in two different ways using Roman numerals'
MIM + MMXIV = MMMXIII or MMCXCIX + MMXIII = MMMXIII There is only one way to write the solution (3013)
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).
Bear in mind that Roman numerals actually are numbers, they are just not the kind of numbers that we presently use, which are called Arabic numerals. Arabic numerals were first used in Europe in the year 976 AD. Roman numerals still have not entirely fallen out of use, although for most purposes we use Arabic numerals.
Notwithstanding todays modern conversion of 1999 and 14 into Roman numerals which are MCMXCIX and XIV respectively inasmuch that there exist credible evidence to suggest that the ancient Romans would have added together the equivalent of 1999 and 14 in either of the following formats:- A: IMM+IXV = MMXIII => (2000-1)+(15-1) = 2013 B: MDCCCCLXXXXVIIII+XIIII = MMXIII => 1999+14 = 2013 Not that for more complicated calculations the ancient Romans would have used an abacus calculating device.
See answer to question: ' How do you add together 1666 and 1999 in two different ways using Roman numerals'
MIM + MMXIV = MMMXIII or MMCXCIX + MMXIII = MMMXIII There is only one way to write the solution (3013)
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).
Bear in mind that Roman numerals actually are numbers, they are just not the kind of numbers that we presently use, which are called Arabic numerals. Arabic numerals were first used in Europe in the year 976 AD. Roman numerals still have not entirely fallen out of use, although for most purposes we use Arabic numerals.
Notwithstanding todays modern conversion of 1999 and 14 into Roman numerals which are MCMXCIX and XIV respectively inasmuch that there exist credible evidence to suggest that the ancient Romans would have added together the equivalent of 1999 and 14 in either of the following formats:- A: IMM+IXV = MMXIII => (2000-1)+(15-1) = 2013 B: MDCCCCLXXXXVIIII+XIIII = MMXIII => 1999+14 = 2013 Not that for more complicated calculations the ancient Romans would have used an abacus calculating device.
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
Notwithstanding todays modern conversion of 999 into Roman numerals which are CMXCIX inasmuch that the ancient Romans in all probability would have added together the equivalent of 666 and 999 in either of the following formats:-A: DCLXVI+IM = MDCLXV => 666+(1000-1) = 1665B: DCLXVI+DCCCCLXXXXVIIII = MDCLXV => 666+999 = 1665QED
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/
The ancient Romans would have worked out 1776 on an abacus counting device as MDCCLXXVI and 1999 as MDCCCCLXXXXVIIII which can be abridged to IMM thus facilitating the speed and ease of subtraction in either of the following formats:- A: IMM-MDCCLXXVI = CCXXIII => (2000-1)-1776 = 223 B: MDCCCCLXXXXVIIII-MDCCLXXVI = CCXXIII => 1999-1776 = 223 Note that in todays modern configuration of Roman numerals 1999 is now considered to be MCMXCIX
CIVIC
The wrong way and the right way which is as follows:- IX+IXX = XXVIII => (10-1)+(20-1) = 28 XXVIII+IMM = MMXXVII => 28+(2000-1) = 2027
Arabic numerals are called that because the European interpretation of those numbers comes from the Arabs. The numerals are called Arabic numerals (even though they do not resemble modern Arabic numerals in the slightest) to distinguish them from Roman numerals.