If the number is part of a casual expression, spell it out. |
If the number is a calendar year, do not spell it out. |
If the number is an age or percentage, do not spell it out. |
If the number begins a sentence, spell it out. Awkward sentences should be reformed. |
If the number is greater than 10, do not spell it out. |
If the number is one through nine, spell it out. |
World War II |
John Doe III |
twenty-one |
one hundred thirty-one |
twenty-five thousand one hundred thirty-one |
ninety bottles |