The APA Publication Manual is one of the most widely used style guides, perhaps because of its logical and consistent approach. It recommends these guidelines for using numbers. Variations in MLA Style, from the MLA Handbook for Writers of Research Papers, can be found at the end of this page.

• Use figures for numbers 10 or larger:

  The 17 ships were in the harbor.

  The store offered 20% off.

  The building was built 50 years ago.

  He will come on the 25th.

• If comparing a number smaller than 10 with one larger than 10, use figures for both.

  Only 2 of the 11 members came.

  Of the 15 toys evaluated, only 6 were considered safe.

  Many differences could be seen between 8th and 10th graders.

  But:

  Only two of the students did well on all 12 assignments.

  (Students and assignments are not being compared.)

• Use figures for numbers preceding a measurement.

  3 feet

  10 kilometers

  2 inches

• Use figures when referring to mathematical functions, fractional quantities, decimals, percentages, and ratios.

  Multiply by 1 1/2 to get the answers.

  an assets-to-debt ratio of 3:1

  They offered a 3% cash discount.

  The average age of kindergartners is 5.2 years.

• Use figures for time, dates, ages, and dollar amounts.

  They arrived at 1:20 p.m. on November 19, 1993.

  You must complete the exam within 50 minutes.

  Only 2 hours and 30 minutes remain.

  Spending 2 weeks away from home was hard for the 9-year-olds.

  He spent only $5.50 on the dinner.

Examples of When To Use Words

• Use words for numbers lower than 10 unless they are covered by specific rules for using figures, above.

  I ordered two cups of coffee.

  She spelled six of the eight words correctly.

  The students worked in groups of three.

• Writing out zero and one when using figures would be confusing unless covered by rules above.

  Please correct my bill to show a zero balance.

• Write out numbers when they are the first word in a sentence, title, or heading.

  Twenty-one of the guests arrived on time.

• Write out simple fractions.

  She wanted only one half of the cake.

  One third of the students went.

Examples of When To Use Both

• For large numbers that are rounded off, combine figures and words:

  The lottery amount was $6 million.

  The city has fewer than 1 million people.

• Use both words and figures for back-to-back modifiers.

  He wanted 2 seven-piece sets.

  The class had 6 ten-year-olds and 7 nine-year-olds.

  OR

  The class had six 10-year-olds and seven 9-year-olds.

• Treat ordinal numbers using the same rules as cardinal numbers:

  the first one

  the 10th one

  the 1st and the 15th

• In literary analyzes, which usually don't involve the use of many numbers, spell out numbers that can be written in one or two words.

• Do not use numerals to begin a sentence.

See The Publication Manual of the American Psychological Association for a full list of rules and examples.

Last updated 02/14/08