Roman Numerals
The Numerals are letters
The method in use in Europe until then used the Roman numerals:
I = 1,
V = 5,
X = 10,
L = 50,
C = 100,
D = 500 and
M = 1000
You can still see them used on foundation stones of old buildings and on some clocks.
The Additive rule
For instance, 13 would be written as XIII or perhaps IIIXX. This is reflected in the Roman language of Latin where 23 is spoken as tres et viginti which translates as three and twenty. You may remember the nursery rhyme Sing a Song of Sixpence which begins
Sing a song of sixpence
A pocket full of rye
Four and twenty blackbirds
Baked in a pie...
Above 100, the Latin words use the same order as we do in English, so that whereas 35 is quinque et triginta (5 and 30), 235 is ducenti triginta quinque (two hundred thirty five).
In the simplest system, using addition only, 99 would be 90+9 or, using only the numbers above, 50+10+10+10 + 5+1+1+1+1 which translates to LXXXXVIIII and by the same method 1998 would be written by the Romans as MDCCCCLXXXXVIII.
The subtractive rule
The Roman language (Latin) also uses a subtraction principle so that whereas 20 is viginti 19 is "1 from 20" or undeviginti. This is also reflected in Roman numerals. This abbreviation makes the order of letters important. So if a smaller value came before the next larger one, it was subtracted and if it came after, it was added.
For example, XI means 10+1=1 (since the smaller one comes after the larger ten) but IX means 1 less than 10 or 9.
But 8 is still written as VIII (not IIX). The subtraction in numbers was only of a unit (1, 10 or 100) taken away from 5 of those units (5, 50 or 500 or from the next larger multiple of 10 (10, 100 or 1000).
Using this method, 1998 would be written much more compactly as MCMXCVIII but this takes a little more time to interpret: 1000 + (100 less than 1000) + (10 less than 100) + 5 + 1 + 1 + 1.
Note that in the UK we use a similar system for time when 6:50 is often said as "ten to 7" as well as "6 fifty", similarly for "a quarter to 4" meaning 3:45. In the USA, 6:50 is sometimes spoken as "10 of 7".
Look out for Roman numerals used as the date a film was made, often recorded on the screen which gives its censor certification or perhaps the very last image of the movie giving credits or copyright information.
Arithmetic with Roman Numerals
Arithmetic was not easy in the Roman system:
CLXXIIII added to XXVIII is CCII
CLXXIIII less XXVIII is CXXXXVI
