 In this system, there is no notation for zero, and the numeric values for individual letters are added together.Each unit (1, 2, ..., 9) is assigned a separate letter, each tens (10, 20, ..., 90) a separate letter, and the first four hundreds (100, 200, 300, 400) a separate letter.The later hundreds (500, 600, 700, 800 and 900) are represented by the sum of two or three letters representing the first four hundreds.