The Roman numeral system is still used today, when writing a century, on monuments, in the names of kings and popes.
This system, based on the Etruscan numbering system, was developed in Ancient Rome. It is made up of capital letters that have different values and is additive, that is, to know what number it is, you have to add the value of each symbol.
1 | 5 | 10 | 50 | 100 | 500 | 1000 |
I | V | X | L | C | D | M |
The roman number system has the following rules
- The letters I, X, C, M can be repeated only three times:
- III = 3
- XX = 20
- CCC = 300
- M = 1000
- V, L y D can not be repeated
- A letter with a minor value written at the right side of other add its value:
- XI = 10 + 1 = 11
- If it is written at the left side we subtract the value
- IX = 10 – 1 = 9
Activity 1: Write each number in the decimal system
a) DCXV
b) MMIX
c) XXXIV
d) CCCXLVIII
e)

f)

Check your answers
Activity 2: Write the following numbers in the Roman system.
- 45
- 126
- 3.405
- 1.874
Check your answers
Un comentario en “Roman number system”