# 羅馬數字

羅馬數字寫錶面
大樓面上羅馬數字 MDCCCLXXXIII，表示呢幢建築物係喺1883年起嘅
**羅馬數字**係古時羅馬使嚟記數嘅方法，後嚟傳咗去歐洲，而今喺世界各地都重不時用到。

羅馬數字一共有七個，即 I（1）、V（5）、X（10）、L（50）、C（100）、D（500）同埋 M（1000）。有套規則寫晒正整數。羅馬數字冇「0」。一般認為羅馬數字只用來記數，唔係運算。

譬如今年係2026年，用羅馬數字寫就係「MMXXVI」。

另一個成日見羅馬數字嘅地方就係鐘面或者錶面，例如右圖，用嚟表示時間嘅一至十二分別寫做：

**I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII**
## 拼寫規則

* 重複：數字I、X、C、M重複幾次，就係佢嘅幾多倍。例如I係1，III就係3；C係100，CC就係200。
* 大到細係加，細到大係減：
	+ 喺大啲嘅數字右邊寫細啲嘅數字，就係大加細。例如VI就係5+1=6。
	+ 喺大啲嘅數字左邊寫細啲嘅數字，就係大減細。例如IV就係5-1=4。
	+ 左減嘅數字只可以係I、X、C。例如45要寫XLV，唔可以寫VL。
	+ 左減嘅數字唔可以超過一個位值，即係V、X可以減I，但係L、C就唔可以減I。例如99要寫XCIX（[100-10]+[10-1]），唔可以寫IC（[100-1]）。
	+ 左減嘅數字只可以一位。例如8係VIII，唔可以寫IIX。
	+ 右加嘅數字最多三位，四位就轉做左減，例如14就係XIV，唔可以寫XIIII。（有例外，睇下面）
* 加線乘一千：
	+ 喺羅馬數字嘅上方加條線，或者加個下標M，表示將個數字乘1000。
	+ 同樣道理，上方加兩條線，就係乘1000000=10002。
* 另外，亦都有5同50寫做IIIII同XXXXX，代替V同L，甚至6同60寫做IIIIII同XXXXXX，代替VI同LX嘅情況。

### 例外

* 四有時會寫IIII，唔寫IV，坊間有傳係因為IV係古羅馬神話主神朱庇特（IVPITER，古羅馬字母無J同U）嘅頭兩個字母，所以避諱，另一種講法係喺鐘錶上面四嘅另一便係八（VIII），寫IV會搞到個設計唔對稱，所以寫IIII，而事實上IIII係英式手寫傳統。
* 喺大細楷羅馬數字未分家之前，排版嗰陣大楷標題會用大楷羅馬數字，細楷內文用細楷羅馬數字。
* 喺英式手寫傳統，以前寫細楷i字尾嘅羅馬數字，最尾一個i會寫j，例如四係iiij，唔係iv。

## 示例

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| 羅馬數字 | 數值 | 拉丁文 |
| --- | --- | --- |
| Ⅰ | 1 | uno |
| Ⅱ | 2 | duo |
| Ⅲ | 3 | tres |
| Ⅳ | 4 | quattuor |
| Ⅴ | 5 | quinque |
| Ⅵ | 6 | sex |
| Ⅶ | 7 | septem |
| Ⅷ | 8 | octo |
| Ⅸ | 9 | novem |
| Ⅹ | 10 | decem |
| Ⅺ | 11 | undecim |
| Ⅻ | 12 | duodecim |
| ⅩⅢ | 13 | tresdecim |
| ⅩⅣ | 14 | quattuordecim |
| ⅩⅤ | 15 | quindecim |
| ⅩⅥ | 16 | sedecim |
| ⅩⅦ | 17 | septendecim |
| ⅩⅧ | 18 | duodeviginti |
| ⅩⅨ | 19 | undeviginti |
| ⅩⅩ | 20 | viginti |
| ⅩⅪ | 21 | viginti unus |
| ⅩⅫ | 22 | viginti duo |
| ⅩⅩⅧ | 28 | duodetriginta |
| ⅩⅩⅨ | 29 | undetriginta |
| ⅩⅩⅩ | 30 | triginta |
| ⅩⅬ | 40 | quadraginta |
| Ⅼ | 50 | quinquaginta |
| ⅬⅩ | 60 | sexaginta |
| ⅬⅩⅩ | 70 | septuaginta |
| ⅬⅩⅩⅩ | 80 | octoginta |
| ⅩⅭ | 90 | nonaginta |
| ⅩⅭⅨ | 99 | nonaginta novem |
| Ⅽ | 100 | centum |
| ⅭⅠ | 101 | centum et unus |
| ⅭⅡ | 102 |  |
| ⅭⅢ | 103 |  |
| ⅭⅩⅭⅨ | 199 | centum nonaginta novem |
| ⅭⅭ | 200 | ducenti |
| ⅭⅭⅭ | 300 | trecenti |
| ⅭⅮ | 400 |  |
| Ⅾ | 500 | quincenti |
| DCCC | 800 |  |
| CM | 900 |  |

 |

| 羅馬數字 | 數值 | 拉丁文 |
| --- | --- | --- |
| Ⅿ | 1,000 | mille |
| ⅯⅭⅮ | 1,400 |  |
| ⅯⅮ | 1,500 | mille quincenti |
| ⅯⅮⅭⅭⅭ | 1,800 |  |
| ⅯⅮⅭⅭⅭⅬⅩⅩⅩ | 1,880 |  |
| ⅯⅮⅭⅭⅭⅬⅩⅩⅩⅣ | 1,884 |  |
| ⅯⅮⅭⅭⅭⅬⅩⅩⅩⅨ | 1,889 |  |
| ⅯⅮⅭⅭⅭⅩⅭ | 1,890 |  |
| ⅯⅮⅭⅭⅭⅩⅭⅨ | 1,899 |  |
| ⅯⅭⅯ | 1,900 |  |
| ⅯⅭⅯⅬⅩⅩⅩⅨ | 1,989 |  |
| ⅯⅭⅯⅩⅭ | 1,990 |  |
| ⅯⅭⅯⅩⅭⅧ | 1,998 |  |
| ⅯⅭⅯⅩⅭⅨ | 1,999 |  |
| ⅯⅯ | 2,000 | duo milia |
| ⅯⅯⅠ | 2,001 |  |
| ⅯⅯⅣ | 2,004 |  |
| ⅯⅯⅤ | 2,005 |  |
| ⅯⅯⅨ | 2,009 |  |
| ⅯⅯⅩ | 2,010 |  |
| ⅯⅯⅩⅬ | 2,040 |  |
| ⅯⅯⅬ | 2,050 |  |
| MMLX | 2,060 |  |
| ⅯⅯⅩⅭ | 2,090 |  |
| ⅯⅯⅭ | 2,100 |  |
| ⅯⅯⅭⅭ | 2,200 |  |
| ⅯⅯⅭⅯ | 2,900 |  |
| ⅯⅯⅯ | 3,000 | tria milia |
| ⅯⅯⅯⅭⅭⅭⅩⅩⅩⅢ | 3,333 | tria milia trecenti triginta tres |
| ⅯⅯⅯⅮⅭⅭⅭⅬⅩⅩⅩⅧ | 3,888 |  |
| Ⅳ | 4,000 | quattuor milia |
| ⅣⅭⅮⅩⅬⅣ | 4,444 |  |
| ⅣⅮⅭⅭⅭⅬⅩⅩⅩⅧ | 4,888 |  |
| ⅣⅭⅯⅩⅭⅠⅩ | 4,999 |  |
| V | 5,000 | quinque milia |
| X | 10,000 |  |
| L | 50,000 |  |
| C | 100,000 |  |
| D | 500,000 |  |
| M | 1,000,000 |  |

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## 參考