Spell out numbers zero through nine. Use numerals for all numbers 10 and above. Superscripts for ordinal suffixes are optional. Use whatever looks best, and stay consistent. Exceptions are noted below.
Right: nine poodles, four rooms, 16 buildings
Right: 15th highest, 21st Street, Sixth Avenue
Right: He teaches ninth grade and acts like a ninth-grader.
Use numerals for ages, percentages, equipment specifications, precise measurements, page numbers and sums of money (when using the symbol “$”).
Right: She has a 2-year-old daughter and a son, 8.
Right: 8 milligrams, 4 degrees below zero
Right: 3-point shot, the 6-foot-4-inch guard
Right: According to the chart on page 4, nearly half of the elementary-age children in Georgia receive a $5 weekly allowance.
For numbers of more than three digits, use a comma after every third digit from right to left.
Right: Piedmont Central will provide housing for 1,100 students.
For numbers beyond thousands that do not involve currency, spell out numbers under 10, and use the appropriate word to describe the quantity.
Right: Nearly three million people live in Chicago.
Right: Apple sold more than 590 million iPhones between 2007 and 2014.
Wrong: According to the United States Department of Agriculture, an estimated 133,000,000,000 pounds of food went uneaten in 2010.
Avoid starting sentences with numbers. If you have no choice, spell out the number unless it’s a year.
Right: Twenty students registered.
Right: 1914 was an important year.