A representation of this number, such as 13 or XIII, can be written with a single alphabet letter. It is usually done by writing the numeral digits from 1 to 9 and then from 14 to 19 under it, like this: 1.. .9 and then 14.. .19. This is because 13 is the only integer between 10 and 20 that cannot be expressed using the digits 0 and either I or 9. So, 13 can be written as one word with an alphabetical character: "I". It can also be written as two words: "first" and "thirteenth". It can also be written as three words: "first", "twelfth", and "thirteenth". It can also be written as four words: "first", "second", "third", and "thirteenth". And it can even be written as all six words in order: "first", "second", "third", "fourth", "fifth", "sixth", "and thirteenth".