Discover how to write and use 21 as XXI in Roman numerals. Master conversions with clear steps by Vedantu. Boost your math skills today! XXI Roman Numerals can be written as 21 by combining the transformed roman numerals such as XXI Is equals to XXI = XX + I = 20 + 1 = 21 . The bigger roman numerals come before the smaller numerals resulting in the correct translation of XXI Roman Numerals. In this post we will show you how to write roman numerals XXI in numbers. XXI is the Roman numeral representation of 21. Here, X represents 10 and I represents 1. Thus, XXI = 10 + 10 + 1 = 21. Therefore, XXI represents the value 21 in Roman numerals. The above value is derived by combining the values of specific Roman numeral symbols used in the system. In Roman numerals, the symbol ' XXI ' is used to represent 21. Mentioned below are the seven symbols used in the ancient numeric system: I - 1 V - 5 X - 10 L - 50 C - 100 D - 500 M - 1000 According to the symbols ... 21 in Roman numerals is xxi . Click to learn how to converst number to Roman numerals. Solve addition, subtraction, conversion questions here.