Grammar: Numbers

Between 90 and 120 chairs are kept in each meeting room.

Between 90 and 120 chairs are kept in each meeting room. The numbers in this sentence are styled correctly. General number style calls for numbers up to and including one hundred to be written out and larger numbers to be styled in numeral form (although newspapers and some other publications often spell out numbers only up to and including nine).

She really is one in a million, isn't she?

She really is one in 1,000,000, isn't she? Informal references to large numbers should be spelled out.

The city's population is 2,245,389.

The city's population is about 2,245,389. Do not use about or approximately when a figure is exact, or round off the number (i.e. "The city's population is about 2.25 million").

There are four chairs in the first room, eleven in the second room, and sixteen in the third room.

There are four chairs in the first room, 11 in the second room, and 16 in the third room. When referring to numbers of like objects when numbers, if appearing in isolation, would typically be styled differently from each other, adopt a consistent style. (If you adhere to the up-to-ten dividing line, rather than the over-one-hundred distinction, to decide whether to spell numbers out or use numerals, all three numbers in this sentence should be in numeral form.)

They counted twenty-six pairs of shoes in the box.

They counted twenty six pairs of shoes in the box. Hyphenate all names of numbers between twenty-one and ninety-nine that consist of two words, whether they appear in isolation or as part of a larger number, as in "Five hundred fifty-two phone calls were made over the course of three days."

This city of three million has come a long way since its humble beginnings.

This city of 3,000,000 has come a long way since its humble beginnings. For improved readability, spell out large round numbers.

One hundred thirty people were killed in the terrorist attacks in Paris.

130 people were killed in the terrorist attacks in Paris. When a number begins a sentence, spell it out regardless of whether it would normally be spelled out or written in numerals. Alternatively, recast the sentence so that the number does not begin the sentence: "In the terrorist attacks in Paris, 130 people were killed."

About 410 million people speak some form of Spanish.

About 410,000,000 people speak some form of Spanish. For orders of magnitude (millions, billions, and so on), use the term for the order of magnitude, rather than hard-to-read sets of zeros divided by commas, for round numbers. For precise numbers, such as 4,877,923, consider rounding off to one decimal place ("4.9 million") except in the rare instance when a precise count is required.

Disco music dominated the charts in the latter half of the 1970s.

Disco music dominated the charts in the latter half of the 1970's. Do not use an apostrophe in a reference to a decade, which should take plural, not possessive, form. (The exception is when the number is elided to two digits, as in "the '70s," but note that the apostrophe precedes the number because it signals that digits have been omitted.)

If you had a machine that produced a hundred dollars for life, what would you be willing to pay for it today?

If you had a machine that produced $100 dollars for life, what would you be willing to pay for it today? Redundantly preceding a numeral with a dollar sign and following it with the word "dollar" is a common error. Also, spell out round numbers like "one hundred" unless the content includes numerous dollar amounts or other figures styled numerically.

Last year, 50,000-60,000 people attended the event.

Last year, 50-60,000 people attended the event. When both numbers in a number range are large round numbers with the same number of digits, do not omit zeros in the first number.

One hundred eighty-three people attended the event.

One hundred and eighty-three people attended the event. If you do spell out a number because it begins a sentence, in American English, avoid the conversational "and" between place values.

The database amounts to about fifty million documents and about 150 billion words.

The database amounts to about fifty million documents and about 150 billion words. When using a term of magnitude (million, billion, and so on), apply the basic rule for spelling out numbers or using numerals: Use a numeral for a number exceeding one hundred and spell out numbers of less than one hundred. When two or more numbers that refer to the same thing are mixed (at least one over and one under one hundred), use numerals consistently. This sentence is correct. (Documents and words are related but not identical.)

The following year, about 2.4 million units were produced.

The following year, about 2,389,000 units were produced. For improved readability, very large numbers should be rounded up and reduced to a decimal fraction to one or two digits.

Three hundred twenty-seven students voted for Mary Jones, and 289 cast a ballot for John Smith.

Three hundred twenty-seven students voted for Mary Jones, and 289 cast a ballot for John Smith. This sentence is technically correct. Normally, numbers above nine or those over one hundred, depending on which of two primary style recommendations one adheres to, are usually referred to with numerals, but one of numerous exceptions is when a number begins a sentence. To minimize exceptions, recast the sentence so that it doesn't begin with a number (for example, "Mary Jones received 327 votes, and 289 students cast a ballot for John Smith").