Below you’ll find a handful of tips about appropriate use of numbers in various contexts.
Isolated, casual references to amounts of money of one hundred dollars or less or one hundred cents or less are usually spelled out (“I made over fifty dollars in one afternoon”; “Remember when a candy bar cost twenty-five cents?”).
Amounts over those limits are generally styled with numerals and a dollar sign, as are smaller amounts when more than one amount is listed and at least one is less than a hundred dollars (“The chair cost $237, and the table was $89”). When amounts of less than and more than a dollar are combined, use dollar signs and figures in that case as well (“The price tags read ‘$0.75’ and ‘$1.25’”).
Numerous instances of monetary figure call for the use of numerals in most cases, but larger rounded figures may be spelled out, even when inconsistent with precise dollar figures (“I made over fifty thousand dollars for the first time last year: $51,500.”) Numbers in the millions and higher orders of magnitude may be in combined numeral and spelled-out form (“The project was budgeted at $2.5 million”).
2. Numerals at the Beginning of a Sentence
Sentences should never begin with a numeral; either spell out the number (“Two thousand eleven was the year the business turned a profit”) or recast the sentence (“The business first turned a profit in 2011”). Another option is to precede the number with the phrase “The year,” but doing so introduces inconsistency if every reference to a year, regardless of position in a sentence, does not follow a repetition of the phrase; that solution is also awkward.
3. Number Ranges
En dashes (or hyphens, employed in place of en dashes on many Web sites) are used in number ranges — for example, to indicate life span, years of rule or years in office, athletic or artistic seasons, or page ranges — as an alternative to “from x to y” or “from x through y.”
An en dash should not be used with the word from. (Incorrect: “He reigned from 1863-1895”; correct: “He reigned from 1863 to 1895” or “He reigned 1863-1895”). The same principle applies for the word between: “Between 250 and 300 people attended,” not “Between 250-300 people attended,” is correct.
Many writers submit manuscripts that feature the letters in ordinal numerals in superscript form — that is, st, nd, rd, and th raised above the font’s baseline. This form is seldom needed when following the style rule that numbers are spelled out up to one hundred, but when ordinals are required (“The ribbon read ‘1st Place’”; “the 101st Airborne Division”), they should be on the baseline, not raised. Instructions for how to change superscript ordinals to baseline ordinals are available through an online search.
Also, when a date is written, the ordinal form is extraneous; simply write “January 1,” not “January 1st.” (In the absence of the month, the date should be spelled out: “Her reply followed on the twenty-first.” If a publication’s number style is to spell numbers out only to ten, the form shown her applies: “Her reply followed on the 21st.”
5. The Plural of Zero
In Merriam-Webster’s Collegiate Dictionary, zeros is the first of two alternatives for the plural of zero. The other, of course, is zeroes. The first choice is not the superior one; it is listed first simply because it is simpler. But many editors follow a convention that, for consistency, the dictionary’s first of more than one alternatives is the standard except when the preference for another is codified in the house style guide.
Therefore, zeros is generally the correct style. Note, however, that the correct spelling of the present-tense verb form meaning “focuses” or “aims” is zeroes (“Disregarding the pursuing planes, he zeroes in on his target”).