With the numbers, I can correspond to a series of numbers to one of the 26 letters of the English language. Like the Roman numeral system, a number adds if the next one in the sequence is smaller, and vice versa if it is larger. Combining the structure of the Roman numerals with the numbers 1, 2, 5, 10, and 20 makes it so that you never have to use more than 3 numbers to express a letter.
