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

Check your answers

Activity 2: Write the following numbers in the Roman system.

• 45
• 126
• 3.405
• 1.874

Check your answers