### Common information. Examples of using roman numerals in date inscriptions

Roman numerals are the numbers first used by the ancient Romans in their numerical system. Roman numerals originated about 500 years BC by way of the Etruscans. The Roman numeral system is decimal but not directly positional and does not include a zero. This system is based on letters of the alphabet, which are combined to signify the sum (or in some cases, the difference) of their values.

Natural numbers can be written by repetition of those letters and/or their combinations. If a greater numeral stands in front of a smaller numeral (XV = 10 + 5 = 15), the values of these numerals are summed (the principle of addition); if a smaller numeral stands in front of a bigger numeral (CM = 1000 – 100 = 900), then the smaller numeral is subtracted from the bigger numeral (the principle of subtraction). The last rule is used solely in order to avoid fourfold replication of the same numeric character.

It should be noted that V (5), L (50) and D (500) cannot be subtracted. On the contrary, I (1), X (10) and C (100) can be subtracted — if they stay in front of the bigger numeral, as described above.

Nevertheless, designers traditionally put «IIII» instead of «IV» (numeral «4») on clock faces:

Sometimes you'll see a Roman numeral with a line over it. This means that you should multiply the value under the line by 1,000. For instance, the Roman numeral «**X**» with a line over it means 10×1,000 = 10,000.

In the Middle Ages, after the printing press had been invented, the year of publication of a book was often denoted by Roman numerals:

Even on the $1 bank note (which is actually a __Federal Reserve note__, not a United States note) we can find the date written in accordance with the Roman numerical system:

As you might guess, that's 1776, i.e. the year of the Declaration of Independence.

The Vatican City State is known for its Papal Basilica of Saint Peter. On the front of it one can see the following inscription written in Latin: «IN HONOREM PRINCIPIS APOST PAVLVS V BVRGHESIVS ROMANVS PONT MAX AN MDCXII PONT VII».

This means: «Paul V Borghese, Supreme Roman Pontiff, in the year 1612, the seventh of his pontificate, erected in honour of the Prince of Apostles». As you can see, the year 1612 AD has been written using Roman numerals, i.e. **MDCXII**.

Saint Petersburg is known as Russia's northern capital. One of its greatest monuments is “**The Bronze Horseman**”, it portrays Russian Emperor __Peter the Great__ sitting on his horse, his outstretched arm pointing towards the River Neva. This monument is located in the Senate Square. There are two inscriptions on the pedestal of the monument, as follows: “ÏÅÒÐÓ ïåðüâîìó ÅÊÀÒÅÐÈÍÀ âòîðàÿ ëѣòà 1782” in Russian and “PETRO Primo CATHARINA Secunda MDCCLXXXII” in Latin. They mean: “Catherine the Second to Peter the First, 1782”.

As you can see, **MDCCLXXXII** in Roman numeral corresponds to 1782 AD.

The U.S. “trime”, or 3 cent, silver coins minted in 1851–1873 had their value written in Roman numerals, just like this:

(image source courtesy of coinauctionshelp.com/ThreeCentsSilver.html)