The numeric system represented by Roman numerals originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers in this system are represented by combinations of letters from the Latin alphabet. Roman numerals, as used today, are based on seven symbols:
| Symbol | I | V | X | L | C | D | M | | --------------------------------------------| | Value | 1 | 5 | 10 | 50 | 100 | 500 | 1000 |
In its simplest form, the numbers 1 to 10 are expressed as follows:
I, II, III, IIII, V, VI, VII, VIII, VIIII, X
Some examples of larger numbers include:
12 as XII 25 as XXV 140 as CXXXX 1954 as MDCCCCLIIII 1990 as MDCCCCLXXXX 2014 as MMXIIII 2017 as MMXVII
Create a javascript function toSimpleRoman that can convert from our modern numbering system (positional Arabic numerals) to Roman numerals, e.g.
> toSimpleRoman(9)
> VIIII
>
> toSimpleRoman(12)
> XII
>
> toSimpleRoman(1990)
> MDCCCCLXXXX
>
> toSimpleRoman(140)
> CXXXX
In a few specific cases, to avoid confusing and hard to read numbers with four characters repeated in succession (such as IIII or XXXX), subtractive notation is used: as in this table
| Number | 4 | 9 | 40 | 90 | 400 | 900 | | -----------------------------------------| | Notation | IV | IX | XL | XC | CD | CM |
The numbers 1 to 10 are thus more commonly expressed in Roman numerals as follows:
I, II, III, IV, V, VI, VII, VIII, IX, X.
Some examples of the modern use of Roman numerals include:
12 as XII 25 as XXV 140 as CXL 1954 as MCMLIV 1990 as MCMXC 2014 as MMXIV 2017 as MMXVII
Create a javascript function toCompactRoman that converts from our modern numbering system to Roman numerals, using the more compact subtractive notation as described earlier in this section, e.g.:
> toCompactRoman(9)
> IX
>
> toCompactRoman(12)
> XII
>
> toCompactRoman(1990)
> MCMXC
>
> toCompactRoman(140)
> CXL