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Roman Numerals

Age 9.6 +

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

Romans used letters from the alphabet rather than figures (digits) to write out their numbers. The letters that they used are listed in the table on the right. So, for example, if a Roman wanted to write the number 150, he would write CL. 

Here are some other examples of numbers written with Roman numerals. Check through all of them to make sure that you understand how the system works.

VI = 6,   VII = 7,  VIII = 8,   XV = 15 

XXX = 30,   LX = 60,   LV = 55 

CC = 200,   DCC = 700,   MMC = 2100

 

The examples above are straightforward and simple. However, there is a slight complication! When a letter that is worth less is written before a letter that is worth more, then you need to do a subtraction to figure out what number is being written. 

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

Roman Numerals examples

Here are some examples of these. 

IV = 4,   IX = 9,   XL = 40,   XC=90,   CM=900

With large numbers, it sometimes helps to underline the pairs of letters where a subtraction is required. For example, ...

CIX = 109,   XCI = 91,    MCMII = 1902,    MMCMLXIV = 2964

The examples that follow become increasingly complex but the same principles apply. Make sure that you understand each of them.Roman Spartan soldier cartoon drawing

XIV = 14,   XX1X = 29,   LIV = 54,   

LVI = 56,   XXIV = 24,   XIX = 19

LIX = 59,   LXVIII = 68,   LXXVII = 77   

CIX = 109,   MMC = 2100,   MCM = 1900   

DCL = 650,   MCMVC = 1995,   MCMIC = 1999,   MIM = 1999

NOTE: As a general rule, only one letter that is worth-less-than-the-one-that-follows is permissible, though this event may occur more than once in a given number. So, for example ...

... IIX is not permissible 

... but XLIX is permissible

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