The numbers that we use today are not the same as the ones the Romans used. Roman numerals were used all over the Roman Empire.
In England, they are still used occasionally, for example, on film credits and clock faces.
Remember that the Romans didn't have a symbol for the number 0.
The Romans used these symbols:
| I = 1 |
| V = 5 |
| X = 10 |
| L = 50 |
| C = 100 |
| D = 500 |
| M = 1000 |
All other numbers can be built using these symbols by adding or subtracting.
A letter placed after another letter means that you add the second letter to the first letter.
A letter placed before another letter means that you subtract the first letter from the second.
You should know the following:
| 1 = I |
| 2 = II |
| 3 = III |
| 4 = IV |
| 5 = V |
| 6 = VI |
| 7 = VII |
| 8 = VIII |
| 9 = IX |
| 10 = X |
| 11 = XI |
| 12 = XII |
We build bigger numbers by adding 10s or Xs in Roman numerals.
| XX = X + X = 20 |
| XXI = XX + I = 20 + 1 = 21 |
| XXX = X + X + X = 30 |
| XXXVII = XXX + VII = 30 + 7 = 37 |
| XL = 50 - 10 = 40 |
| XLVIII = XL + VIII = 40 + 8 = 48 |
| XLIX = XL + IX = 40 + 9 = 49 |
| LIV = L + IV = 50 + 4 = 54 |
| LX = 50 + 10 = 60 |
| LXVII = LX + VII = 60 + 7 = 67 |
| LXX = L + XX = 50 + 20 = 70 |
| LXXX = L + XXX = 50 + 30 = 80 |
| LXXIV = L + XXXIV = 50 + 34 = 84 |
| XC = 100 - 10 = 90 |
| XCVI = XC + VI = 90 + 6 = 96 |
We build even bigger numbers by adding 100s, 500s or 1000s or Cs, Ds and Ms in Roman numerals.
| CC = C + C = 200 |
| CCCXI = C + C + C + X + I = 300 + 10 + 1 = 311 |
| CD = 500 - 100 = 400 |
| CDXLIV = CD + XL + IV = 400 + 40 + 4 = 444 |
| D = 500 |
| DCCC = D + C + C + C = 500 + 300 = 800 |
| CM = 1000 - 100 = 900 |
| M = 1000 |
Larger numbers are built from smaller numbers.
| MCC = M + C + C = 1000 + 200 = 1200 |
| MCCCI = M + C + C + C + X + I = 1000 + 300 + 1 = 1311 |
| MCD = M + CD = 1000 + 400 = 1400 |
| MCM = M + CM = 1000 + 900 = 1900 |
Example
Convert 1895 and 1948 to Roman numerals.
Answer
Build the numbers using smaller numbers that you know.
Then string them together in a line.
1895 = 1000 + 800 + 90 + 5 = M + DCCC + XC + V = MDCCCXCV
1948 = 1000 + 900 + 40 + 8 = M + CM + XL + VIII = MCMXLVIII
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