Rule 1. The numbers one through ten should be spelled out; use figures for numbers greater than ten.

Examples I want five copies.
I want 15 copies.

Rule 2. With a group of related numbers where one number is above 10 in a sentence, write them all in figures. Use words if all related numbers are 10 or below.

Correct I asked for 5 pencils, not 50.
My two cats fought with their one cat.

Incorrect I asked for five pencils, not 50.

Rule 3. If the numbers are unrelated, then you may use both figures and words.

Example I asked for 30 pencils for my five employees.

Rule 4. Use figures for tables and statistics.

Rule 5. Always spell out simple fractions and use hyphens with them.

Examples One-half of the pies have been eaten.
a two-thirds majority

Rule 6. A mixed fraction can be expressed in figures unless it is the first word of a sentence.

Example We expect a 5 ½ percent wage increase.
Five and one-half percent was the maximum allowable interest.

Rule 7. The simplest way to express large numbers is best.

Example 4 million dollars OR $4 million OR four million dollars (not $4,000,000)
Be careful to be consistent within a sentence.

Correct You can earn anywhere from $500 to $5,000,000.

Incorrect You can earn anywhere from $500 to $5 million.

Rule 8. Write decimals in figures. Put a zero (0) in front of a decimal unless the decimal itself begins with a zero.

Example It grew 0.79 of a foot in one year.
It grew .07 of a foot in one year.

Rule 9. When writing large numbers of five or more digits, use a comma where the comma would appear in the figure format. Use the word and only where the decimal point appears in the figure format.

Example $1054.21 (One thousand fifty-four dollars and twenty-one cents)
$15,768.13 (Fifteen thousand, seven hundred sixty-eight dollars and thirteen cents)

Rule 10. The following examples apply when using dates:

Examples The meeting is scheduled for June 30.
The meeting is scheduled for the 30^th of June.
We have tricks played on us on April 1.
The 1^st of April scares some people.

Rule 11. Hyphenate all compound numbers from twenty-one through ninety-nine.

Example Forty-three people were injured in the train wreck.

Rule 12. Do not hyphenate one hundred, two hundred, etc.