Never begin a sentence with a figure, unless it begin with a year.
Examples: Two hundred bugs crawled. Five flowers grew. 1776 was when the Declaration of Independence was signed.
Use roman numerals to describe wars and show sequences dealing with people.
Examples: World War I, Pope John Paul II
For ordinal numbers, spell out first through ninth and use figures for 10th + when describing order in time or location. Some ordinal numbers (politically and geographic) , should use figures in all cases.
Examples: Second base, 10th in a row. Examples: 3rd District Court, 9th ward.
If no usage is specified for cardinal numbers, spell out numbers below 10 and use figures for numbers 10 +.
Example: Bertha had four children and 11 grandchildren.
When referring to money, use numerals. For cents or amounts of $1 million or more, spell the words cents, million, billion, trillion etc.
Examples: $26.85, $100,600, $7 million, 4 cents.
Sara Nabhan, writer