How it works
To convert between Arabic and Roman numerals, use the following translation table.
| Roman | Arabic |
|---|---|
| M | 1000000 |
| D | 500000 |
| C | 100000 |
| L | 50000 |
| X | 10000 |
| V | 5000 |
| M | 1000 |
| D | 500 |
| C | 100 |
| L | 50 |
| X | 10 |
| V | 5 |
| I | 1 |
Smaller numbers before larger numbers are subtracted from the larger number. Smaller numbers after larger numbers are added to the larger number.
Take each number in turn. Convert it into its Roman equivalent. In this example, P is a multiple of 10 and Q is a multiple of 5, half the value of P. R is a multiple of 10, one tenth the value of P. 'x' is used here to represent a possible multiple of ten. Note, there is no zero value.
| Arabic | Roman equivalent |
|---|---|
| 1x | R |
| 2x | RR |
| 3x | RRR |
| 4x | RQ |
| 5x | Q |
| 6x | QR |
| 7x | QRR |
| 8x | QRRR |
| 9x | RP |
| 10x | P |
The patterns 45, 49, 95, 99..95, 99 and 99..9 can all be optimised to just two numerals, although traditionally, this would not be used. Traditionally, IIII was sometimes used in place of IV (to avoid confusion with the shortened form of the name IVPPITER [Jupiter]). This script will only output the normal IV variant, though it will accept both forms as input.
Sample output
Days since 01/01/1970 (UNIX epoch):
XXII
Time on the server (in seconds):
XXMDXLIV
Try it
For Roman to Arabic conversion, use _M to replace M etc.
To download the script(s), and see the script license, use the links on the navigation panel at the top of this page.
(Note: this page shares the strict doctype used by most pages on this site, but the underline element used by this script requires a transitional doctype, so yes, this page will not validate. If you want your page to validate, make sure you use a transitional doctype when using this script.)