• Spell out zero through nine. Use Arabic numerals for 10 and greater. If more than one numeral appears in the same sentence—and all of them refer to the same category of item—do not use numerals for some and spell out others. If according to the rule you must use numerals for one of the items in a given category, then for consistency’s sake use numerals for them all.

He had four books on his desk.
She planted 12 bulbs in her garden.
There were 5 students in the morning session and 12 students in the afternoon.

• Use a comma with numerals of 1,000 and above (except dates).

5,000
42,000

• Use numerals when referring to academic credit.

The student earned 2.5 hours of credit.

• Use numerals when referring to a page number.

The passage begins on page 5.

• See also ages, percentages.