# To Write Complex Roman Numerals, You Must Keep the Following Rules in Mind

**WRITING COMPLEX ROMAN NUMERALS**

IThe easiest way to note down a number is to make that many marks - little I’s. Thus I means 1, II means 2, III means 3. However, four strokes seemed like too many....

VSo the Romans moved on to the symbol for 5 - V. Placing I in front of the V — or placing any smaller number in front of any larger number — indicates subtraction. So IV means 4. After V comes a series of additions - VI means 6, VII means 7, VIII means 8.

XX means 10. But wait — what about 9? Same deal. IX means to subtract I from X, leaving 9. Numbers in the teens, twenties and thirties follow the same form as the first set, only with X's indicating the number of tens. So XXXI is 31, and XXIV is 24.

LL means 50. Based on what you've learned, I bet you can figure out what 40 is. If you guessed XL, you're right = 10 subtracted from 50. And thus 60, 70, and 80 are LX, LXX and LXXX.

CC stands for centum, the Latin word for 100. A centurion led 100 men. We still use this in words like "century" and "cent." The subtraction rule means 90 is written as XC. Like the X's and L's, the C's are tacked on to the beginning of numbers to indicate how many hundreds there are: CCCLXIX is 369.

DD stands for 500. As you can probably guess by this time, CD means 400. So CDXLVIII is 448. (See why we switched systems?)

MM is 1,000. You see a lot of Ms because Roman numerals are often used to indicate dates. For instance, this page was written in the year of Nova Roma's founding, 1998 CE (Common Era; Christians use AD for Anno Domini, "(in the) year of our Lord". That year is written as MCMXCVIII. But wait! Romans counts years from the founding of Rome, ab urbe condita (753 BC). By that reckoning (753 + 1998) this is 2751, or MMDCCLI.

RULES

- Placing a number AFTER an equal or larger number is addition: e.g. put the I (1) after the V (5) = VI (6); put the C (100) after the D (500) = DC (600). N.B. V, L and D are never subtracted this way.

- You can “add” the
**same number(except V, L and D) consecutively up to three**times (NOT four). Examples: - V + I + I + I= VIII (8).
- X + X + X= XXX (30)
- L + X + X + X= LXXX (80)
- C + L + X + X + X= CLXXX (180)
- C + C + C = CCC (300)
- M +
**C + C+ C + I + I + I**= MCCCIII (1,303) - M + M + M= MMM (3,000)

Starting at 5,000, writing either a bar above a Roman numeral or placing parentheses around the Roman numeral can indicate multiplication by 1,000. __

**M + M + M + M + M**= V (5,000)

- Instead of adding four consecutive identical numbers, you subtract one (ten, or one hundred) from the next largest number.

- Placing a smaller number
**BEFORE a larger number is subtraction**. - I before V = 5 – 1 = IV (4)
- I before X = 10 – 1= IX (9)
- X before L = 50 – 10 = XL (40)
- X before C= 100 – 10= XC (90)
- C before D= 500 – 100 = CD (400)
- C before M= 1,000 – 100 = CM (900)

- You can combine coherent units of numbers within a larger number.

Taken from with modifications

**WRITING COMPLEX ROMAN NUMERALS**

- D = 500
- XL = 40
- IV = 4
- DXLIV = 544

Taken from with modifications

**WRITING COMPLEX ROMAN NUMERALS**

- To form a complex number, always
**start by forming the largest place first (the leftmost number)**, and work your way to the smallest place (the last number at theright). For example, to form the number 1,678… - Start by forming 1,000 (1 M)
- Then form 600 (500 + 100, D + C)
- Then form 70 (50 + 10 + 10, L + X + X)
- Then form 8 (5 + 1 + 1 + 1 = VIII)
- ANSWER: MDCLXXVIII

Exercises

- Find the Roman numeral equivalents for the following:
- 1976 (year of Mr. Chang’s birth)
- 2005 (the year this document was made)
- 2046 (title of a movie)
- 1776 (signing of the Declaration of Independence)
- 753 (founding of Rome as a monarchy, i.e. rule by kings, BC)
- 509 (end of Monarchy; beginning of the RomanRepublic, BC)
- 49 (Caesar crosses the Rubicon, BC)
- 27 (Augustus becomes the first emperor of Rome, BC)
- 476 (fall of the Western Roman Empire)
- 1453 (fall of the Eastern Roman Empire)
- 1865 (end of the US Civil War)
- 202 (battle at Zama, end of Second Punic War, BC)

- What numbers are the following?
- XXXVII
- XIV
- DCLXVI
- MCMLXXVIII
- CCX
- XCIX
- CDIV
- CDXLIV

- Give the Latin word the resulting number:
- Decem minus quinque est …
- Unus plus duo est …
- Tres et quattuor sunt …
- Quot sunt sex minus duo?
- Quid est octo et unus?

- Give the Latin (use Latin dictionary) for how many of each body part you have
- oculus, -ī
- ōs, oris
- pēs, pedis
- caput, capitis
- bracchium, bracchiī

- For each of the following terms, identify the root number involved and write the root Latin word for this number:

Taken from with modifications

**WRITING COMPLEX ROMAN NUMERALS**

- century
- decade
- millennium
- sextuplets
- percentage
- tricycle
- octagon
- bicentennial
- quarter
- unison

Taken from with modifications