In nontechnical writing some numbers are spelled out, and some are expressed in figures. Numbers expressed in figures are called numerals.
Numbers Spelled Out
In general, spell out cardinal and ordinal numbers that can be written in one or two words.
Spell out any number that occurs at the beginning of a sentence.
New Hampshire is one of the original thirteen states.
There are twenty-seven students in the class.
Alaska was the forty-ninth state to join the Union.
Sixteen hundred fifteen delegates attended.
Numerals
In general, use numerals to express numbers that would be written in more than two words.
Mount Mitchell, the highest mountain in the eastern United States, is 6,684 feet tall.
In 1790 the total population of the United States (according to the first census) was 3,929,214.
In 1984 Joe W. Kittinger covered 3,535 miles in eighty-three hours and fifty-three minutes, setting a record for balloon flight.
Very large numbers are often written as a numeral followed by the word million or billion.
The surface of the earth is close to 197 million square miles.
If related numbers appear in the same sentence and somehow can be written out while others should appear as numerals, use all numerals.
Edgar ranked 65th in the class; his brother ranked 119th.
1. Money, decimals and percentages.
Use numerals to express amounts of money, decimals and percentages.
$897 million 1.2 kilograms $3.50 5 percent
Amounts of money that can be expressed in one or two words, however, should be spelled out.
forty-five cents two thousand dollars
2. Dates and time
Use numerals to express the year and day in a date and to express the precise time with the abbreviation A.M. and P.M.
The Soviet Union launched Sputnick I, the first manufactured satellite to orbit the earth, on October 4, 1957.
She went to the meeting at 4:15 P.M.
Spell out expressions of time that do not use the abbreviation A.M. or P.M.
She set her alarm clock for five o’clock.
To express a century when the word century is used, spell out the number. Likewise, to express a decade when the century is clear from the context, spell out the number.
In the twentieth century the nation experienced the greatest economic depression of its history.
The Great Depression of the thirties was a severe national economic crisis.
When a century and a decade are expressed as a single unit, use numerals followed by an -s.
In the 1930s the federal government developed many new programs to ease the crisis.
3. Addresses
Use numerals for numbered streets and avenues over ten and for all house, apartment, and room numbers. Spell out numbered streets and avenues of ten or under.
1854 West 66th Street Apartment 8C 20 Second Avenue
4. References
Use numerals to express page, line, act, and scene numbers and the like.
Look on pages 20 and 59 for information about Pablo Casals.
Read lines 1-80 in Book I of the Iliad.
We rehearsed Act II, Scenes 3 and 4, of the play.