# Roman Numerals

Write a function to convert from normal numbers to Roman Numerals.

The Romans were a clever bunch. They conquered most of Europe and ruled

it for hundreds of years. They invented concrete and straight roads and

even bikinis. One thing they never discovered though was the number

zero. This made writing and dating extensive histories of their exploits

slightly more challenging, but the system of numbers they came up with

is still in use today. For example the BBC uses Roman numerals to date

their programmes.

The Romans wrote numbers using letters - I, V, X, L, C, D, M. (notice

these letters have lots of straight lines and are hence easy to hack

into stone tablets).

`1 => I 10 => X 7 => VII`

There is no need to be able to convert numbers larger than about 3000.

(The Romans themselves didn't tend to go any higher)

Wikipedia says: Modern Roman numerals ... are written by expressing each

digit separately starting with the left most digit and skipping any

digit with a value of zero.

To see this in practice, consider the example of 1990.

In Roman numerals 1990 is MCMXC:

1000=M

900=CM

90=XC

2008 is written as MMVIII:

2000=MM

8=VIII