What are Roman Numerals?

Roman numerals were a type of number used in Europe before the introduction of Arabic numerals (actually Indian numerals), and they are now less commonly used. It was produced later than the Chinese digits in Oracle, and later than the Egyptian decimal digits. However, its emergence marked the progress of an ancient civilization. It just doesn't have the number 0.

Roman numerals

Roman numerals are more than 2000 years older than Arabic numerals and originated in

Roman numerals are

Once, a Roman scholar saw an introduction to 0 in the manual. He thought that 0 was very useful for counting, so he ignored some of the Papal bans and quietly recorded some about 0 in his works. And secretly spread some knowledge about 0 and the role it plays in operations. When the Pope knew about this, he immediately sent him to prison and put him in prison. The pope also said tantrums: "The sacred number, inviolable, was created by God. Never allow the evil 0 to come in, and stain the sacred number!"

Later, the scholar was tortured, and he could no longer write with a pen. But after all, darkness can't overcome light. Once people realize the important role of zero, they will break through the shackles of the church desperately and use it boldly.

In 725 AD, Bede and his colleagues had used zero and used the letter N (N is short for nulla, which means zero in Latin) to represent zero.

The most common Roman numerals are the dial symbols of clocks: , , , , , , , , , X, , ...

Periodic Table of the Elements: Groups IA, IIA, IIIA, IVA, VA, VIA, VIIA, IB, IIB, IIIB, IVB, VB, VIB, VIIB, VIII.

Corresponding to the Arabic numerals (that is, the numbers currently used internationally) are 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ... (Note: Arabic numerals were actually invented by the ancient Indians. , Which was later introduced into Europe by Arabs and was mistakenly referred to as Arabic numerals by Europeans.)

Basic characters	I	V	X	L	C	D	M
The corresponding Arabic numbers are represented as	1	5	10	50	100	500	1000

1. Write the same number in succession, and the number represented is equal to the number obtained by adding these numbers, such as: III = 3;

2. The small number is to the right of the large number, and the number represented is equal to the number obtained by adding these numbers, such as: = 8, = 12;

3. Small numbers (limited to I, X, and C) are to the left of large numbers, and the number represented is equal to the number obtained by reducing large numbers, such as: IV = 4, = 9;

4. In normal use, consecutive numbers should not be repeated more than three times;

5. Draw a horizontal line over a number to indicate that the number is 1000 times larger.

There are two things to note:

1. Any one of the basic numbers I, X, and C, or the number used in combination with itself or on the right side of a large number, cannot exceed three; only one can be used on the left side of a large number

2. Cannot put any one of the basic numbers V, L, D as a decimal number on the left side of the large number and use the subtraction method to form the number; on the right side of the large number, the number is added to form the number.

· Single digit example

-1, -2, -3, -4, -5, -6, -7, -8, -9

· Ten digit example

X-10, X-11, X-12, XIII-13, XIV-14, XV-15, XVI-16, XVII-17, XVIII-18, XIX-19, XX-20, XXI-21, XXII- 22, XXIX-29, XXX-30, XXXIV-34, XXXV-35, XXXIX-39, XL-40, VL-45, XLIX (IL) -49, L-50, LI-51, LV-55, LX -60, LXV-65, LXXX-80, XC-90, XCIII-93, VC-95, VCIII-98, VCIV (IC) -99

· Hundreds example

C-100, CC-200, CCC-300, CD-400, LDXL (XD) -490, LDVL (VD) -495, LDVLIV (ID) -499, D-500, DC-600, DCC-700, DCCC 800 CM900 CMXCIX IM 999

· Thousand digit example

M-1000, MC-1100, MCD-1400, MD-1500, MDC-1600, MDCLXVI-1666, MDCCCLXXXVIII-1888, MDCCCXCIX (MDCCCIC) -1899, MCM-1900, MCMLXXVI-1976, MCMLXXXIV-1984, MCMXC (MXM ) -1990, MM-2000, MMMCMXCIX (MMMIM)-3999

· Thousands or more examples

-65,259,

134,945,584,

183,650

Conversion of decimal numbers to Roman numerals from 0 to 3999:

  #include <bits / stdc ++. h>
 using namespace std;
 class Solution {
 public:
 string intToRoman (int num) {
 char * c [4] [10] = {
 {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"},
 {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"},
 {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"},
 {"", "M", "MM", "MMM"}
 };
 string roman;
 roman.append (c [3] [num / 1000% 10]);
 roman.append (c [2] [num / 100% 10]);
 roman.append (c [1] [num / 10% 10]);
 roman.append (c [0] [num% 10]);

 return roman;
 }
 };

The "IIII" mark is unique in the 14th century, because Charles V of France ordered that the use of "IV" was not allowed. He believed that "IV" contained insults, and therefore "IV" must be written as "IIII".

Chapter numbers of books and documents written in Latin characters such as public memorial buildings, clocks, calendars, TV shows, year of production, English, French, etc. (multipurpose

In July 2015, Rome, Italy, stated that it would abandon the use of Roman numerals because it was too complicated for modern people. Parliament has ordered that street signs and official documents be changed to Italian. The Roman City Council passed the bill, and the indoor street signs, identification documents, bills and official documents will be changed to Italian. For example, the Roman numeral "II" of the number 2, will be changed to "secondo" in Italian.

According to the Italian National Bureau of Statistics, only Rome, the capital of Italy, uses Roman numerals, and officials hope that the same number system will be used throughout the country. Although street signs or official documents will not be changed immediately, new documents such as ID cards will be issued.

When Rome announced this new measure, it was a "cultural suicide" that was criticized. The authorities took the lead in destroying Rome's precious cultural assets, and the use of Italian writing was not easy. The cultural community further stated that preserving Roman numerals not only has cultural value, but also an identity that affects the education of the new generation in the future, and calls on relevant departments to think twice. ^[1]

Subsequently, the Rome municipal government came forward to rumor that this order was just a standardization of the relevant database in accordance with the requirements of the Italian National Bureau of Statistics. The city government has no intention to abolish Roman numerals. "