# Roman Numerals

Roman numerals are combinations of the seven letters

*I = 1**V = 5**X = 10**L = 50**C = 100**D = 500**M = 1000*

Roman numbers are expressed by adding or subtracting combinations of the number values of the letters.

- smaller numbers before larger numbers are subtracted
- smaller number after larger numbers are added

Note that Roman numerals are without zero.

Large numbers are indicated with horizontal lines above them. With a horizontal line the number should be multiplied by 1000.

### Example - the Roman number 51

*LI => 50 + 1 = 51*

### Example - the Roman number 9

*IX => -1 + 10 = 9*

### Example - Years

*MCMLXXXII => 1000 + (-100 + 1000) + 50 + 10 + 10 + 10 + 1 + 1 = 1982**MCMLXXVII => 1977*

### Example - Large Roman Numbers

*V => 5 x 1000 = 5000*

### Example - some common Roman numbers

*1 = I**2 = II**3 = III**4 = IV**5 = V**6 = VI**7 = VII**8 = VIII**9 = IX**10 = X**11 = XI**12 = XII**13 = XIII**14 = XIV**15 = XV**16 = XVI**17 = XVII**18 = XVIII**19 = XIX**20 = XX**30 = XXX**40 = XL**50 = L**60 = LX**70 = LXX**80 = LXXX**90 = XC**100 = C**150 = CL**200 = CC**300 = CCC**400 = CD**500 = D**600 = DC**700 = DCC**800 = DCCC**900 = CM**1000 = M**1600 = MDC**1700 = MDCC**1900 = MCM*

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