Spell out numbers that are ten or less. Write the number for higher numbers. For example, you would spell out three, but write 26.
Use words for very large numbers. When you are dealing with millions, billions and trillions, you should use the word because it's easy to understand. For example, you would write "43 million" instead of "43,000,000."
Start a sentence with a spelled out number. You should not start a sentence with a numeral-twenty-six," not "26."
Hyphenate two-digit numbers. When you spell out larger numbers, you should hyphenate only the two-digit numbers. For example, you may write "five hundred eighty-three."
Use numerals for statistics and measurements. You can write "9 percent" or "5 inches."
Write out ordinal numbers, such as "third place." However, for ordinal numbers past the tenth, you can use the numeral.