The Number Rule
Most style guides agree:
 Numbers between one and nine should be spelled out. Numbers 10 or above should be written in Arabic numerals. (Arabic numerals = the way you write numbers in Math class).
Study the following examples:
Wrong  Correct 
I have 3 cats.  I have three cats. 
There are twentyfive students in my class.  There are 25 students in my class. 
My cousin is 5 years old.  My cousin is five years old. 
The gunman killed ten people.  The gunman killed 10 people. 
I ate 2 pieces of cake.  I ate two pieces of cake. 
Exceptions
Like every rule, this rule has exceptions. For example, you may choose to break this rule when writing:
Times 

Dates 

Scores 
The final score was 3–7. 
Instructions for the Quiz
Choose the sentence that is written correctly.
Quiz