21 is valid Arabic numeral. Here we will explain how to read, write and convert the Arabic numeral 21 into the correct Roman numeral format. Please have a look over the Roman numeral table given below for better understanding of Roman numeral system. As you can see, each letter is associated with specific value.
The Roman numeral representation of Arabic numeral 21 is XXI.
If you are aware of Roman numeral system, then converting Arabic numeral 21 to Roman numeral is very easy. Converting 21 to Roman numeral representation involves breaking up the numeral into place values as shown below.
|10 + 10 + 1|
|X + X + I|
We need to combine all converted roman numerals together. As per the rule highest numeral should always precede the lowest numeral to get correct representation. In modern world, the number 21 should be used as it is until or unless it represents an ordinal value. In case of any ordinal value, you can use XXI instead of 21. For any numeral conversion, you can also use our roman to number converter tool given above.