Write out numbers zero through ten in word form. Numbers after ten can be written as a numeral, but they can also be written as a word.
Correct: Zackary Arthur will be nine years old on his birthday.
Incorrect: Zackary Arthur will be 9 years old on his birthday.
Exceptions are made for dates, times, scores, page numbers, and for graphs or charts that may appear in a document. Avoid starting a sentence with a numeral; instead, write the number out when it starts a sentence. Furthermore, a Roman numeral is nearly always used in World War II; never use an Arabic 2. Here are some additional facts about numbers and their use in writing.