Roman numeral conversion

To convert an Arabic number into a Roman numeral, the following Roman numeral conversion rule can be used.

To make the Roman numeral for the Arabic number 2, for example, the Roman numeral I is added to the same Roman numeral I making the Roman numeral II. Therefore, Roman numeral II is equal to the number 2.

1 = I

2 = I + I = II

3 = I + I + I = III

Roman numeral conversion rule

Example: 4 = 5 - 1 or V - I. V - I is written in Roman numeral form as IV.

As a Roman numeral conversion rule, when a letter representing a number of lesser value (I before V) appears to the left of a letter of greater value (V after I), the lesser value (I) is subtracted from the greater value (V).

Math worksheets practice

Arabic numbers	Roman mathematical equivalent	Roman numerals
9	X - I (10 - 1)	IX
20	XXX - X (30 - 10)	XX
40	L - X (50 - 10)	XL
90	C - X (100 - 10)	XC

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