Numbers have two basic forms: digits (7, VII, vii) and phonetic spelling (seven). It's easy to ignore the difference between the two when speaking but writing presents a conundrum: which do you use, the phonetic spelling or the digit? Can you say 4 o'clock, or is it always four o'clock? How many dogs can make a fur coat: one hundred one dalmatians or one hundred and one dalmatians? Are there around seven billion people in the world, 7 billion people, or 7,000,000,000 people? Is this something only nineties kids remember? Or is it Nineties kids? 90's kids? '90s kids?
In general, numbers are spelled out when they are simple and left as digits when they get complicated. This grammar section isn't about how words work in general though: let's examine both how numbers are written into text and when it is and is not appropriate to spell a number out.
In general, numbers are spelled out when they are simple and left as digits when they get complicated. This grammar section isn't about how words work in general though: let's examine both how numbers are written into text and when it is and is not appropriate to spell a number out.
When to Spell Numbers Out
The foundation of usage rules is the desire to keep writing as clear and simple as possible. The most basic rule for spelling out numbers is to do so when it makes sense. For instance, none, one, and two are among the hundred most frequently used words in the English language, and numbers three through ten are all found in the top 250 words. Therefore, it makes sense to have this rule:
1. Numbers from zero to ten are always spelled out.
Let's keep counting up. Eleven, twelve, thirteen... all the digits up to twenty have the same thing in common: all are only one word long just like zero through ten. Next comes 21, which is spelled out as two words connected with a hyphen: twenty-one. The same holds true for twenty-two, twenty-three, and all the integers up to thirty, which return to one word in length. Next is thirty-one, and now a pattern forms: except for the multiples of ten, all the numbers from 21 to 99 have two words. One hundred is also two words, and then after that is 101--with one hundred one, the numbers need three words to be expressed. This holds true until one hundred twenty-one introduces four words, and so on ad infinitum.
As the number of words it takes to express a number increases, the less sense it makes to spell that number out. This creates the second rule of spelling numbers:
2. It is up to the author's preference to spell out one- or two-word numbers, but larger numbers should use digits.
Leaving these spellings up to the writer's discretion explains the variance in titles of films and texts: 12 Angry Men is just as valid as Thirteen Ghosts. It also works when counting down just as well as up: half, two-thirds, and one-tenth are just as valid as 1/2, 2/3, and 0.1. However, 23/79 and .346 are much easier to comprehend than twenty-three-seventy-ninths and point-three-four-six. The more complicated a number is, the better off the writer will be if they express it as a digit. There is one big exception, however:
3. Digits cannot start a sentence.
One of the basic rules of grammar is that sentences all start with a capital letter. Digits don't have letters. Thus, if a writer wants to start a sentence with a number, it has to be spelled out: 47% of respondents supported the measure is incorrect and should be written as Forty-seven percent of respondents supported the measure. While satisfying grammatical standards, the second sentence is more difficult to read than the first, so the best move this author could make is to restructure the sentence completely so the number doesn't start the sentence: Barely less than half the respondents (47%) supported the measure.
1. Numbers from zero to ten are always spelled out.
Let's keep counting up. Eleven, twelve, thirteen... all the digits up to twenty have the same thing in common: all are only one word long just like zero through ten. Next comes 21, which is spelled out as two words connected with a hyphen: twenty-one. The same holds true for twenty-two, twenty-three, and all the integers up to thirty, which return to one word in length. Next is thirty-one, and now a pattern forms: except for the multiples of ten, all the numbers from 21 to 99 have two words. One hundred is also two words, and then after that is 101--with one hundred one, the numbers need three words to be expressed. This holds true until one hundred twenty-one introduces four words, and so on ad infinitum.
As the number of words it takes to express a number increases, the less sense it makes to spell that number out. This creates the second rule of spelling numbers:
2. It is up to the author's preference to spell out one- or two-word numbers, but larger numbers should use digits.
Leaving these spellings up to the writer's discretion explains the variance in titles of films and texts: 12 Angry Men is just as valid as Thirteen Ghosts. It also works when counting down just as well as up: half, two-thirds, and one-tenth are just as valid as 1/2, 2/3, and 0.1. However, 23/79 and .346 are much easier to comprehend than twenty-three-seventy-ninths and point-three-four-six. The more complicated a number is, the better off the writer will be if they express it as a digit. There is one big exception, however:
3. Digits cannot start a sentence.
One of the basic rules of grammar is that sentences all start with a capital letter. Digits don't have letters. Thus, if a writer wants to start a sentence with a number, it has to be spelled out: 47% of respondents supported the measure is incorrect and should be written as Forty-seven percent of respondents supported the measure. While satisfying grammatical standards, the second sentence is more difficult to read than the first, so the best move this author could make is to restructure the sentence completely so the number doesn't start the sentence: Barely less than half the respondents (47%) supported the measure.
How to Spell Numbers
Between 20 and 100: any number not divisible by ten (twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety) consists of two words. If you are spelling out one of these digits, you must hyphenate the words. For example, 97 becomes ninety-seven and 53 becomes fifty-three.
Numbers 101 to 199: Do not put a hyphen or the word and between the hundreds value and the tens value: one hundred one to one hundred ninety-nine. Repeat for all further multiples of 100.
1,000+: When writing out numbers, place commas between numbers in the same places they would appear in the digit (thousands place, millions place, billions place, etc.) For example, the number 4,233,658,902 would be written as four billion, two hundred thirty-three million, six hundred fifty-eight thousand, nine hundred two.
Fractions: Place a hyphen where the divisor line would go: 2/3 becomes two-thirds, and 11/16 becomes eleven-sixteenths. Hyphens are also used when tying a fraction to an integer: two-and-a-half.
Decimals: express them as a fraction or don't write them out at all. Same does for exponents, negative numbers, and roots (though pi is often spelled out).
Years: If a year is expressed by spelling rather than digits, it is first bisected at the hundreds place into two separate digits, and then those are spelled out. For example, 1984 is split into 19 and 84, and is then spelled as nineteen eighty-four, not one thousand, nine hundred eighty-four.
Decades and centuries: If these are spelled out, lowercase letters are always used (the sixties, the eighteenth century)
Numbers in dialogue: When a character speaks a number in their story dialogue, each digit is spelled out and connected by a hyphen. For example, Barry enunciated the address slowly. "Thirteen-five-oh-nine Broadway. Is that downtown?" This is the only time decimals are spelled: "There is a point-zero-three-five percent chance of statistical error," Rodney said, confirming the panel's worst fears.
Numbers 101 to 199: Do not put a hyphen or the word and between the hundreds value and the tens value: one hundred one to one hundred ninety-nine. Repeat for all further multiples of 100.
1,000+: When writing out numbers, place commas between numbers in the same places they would appear in the digit (thousands place, millions place, billions place, etc.) For example, the number 4,233,658,902 would be written as four billion, two hundred thirty-three million, six hundred fifty-eight thousand, nine hundred two.
Fractions: Place a hyphen where the divisor line would go: 2/3 becomes two-thirds, and 11/16 becomes eleven-sixteenths. Hyphens are also used when tying a fraction to an integer: two-and-a-half.
Decimals: express them as a fraction or don't write them out at all. Same does for exponents, negative numbers, and roots (though pi is often spelled out).
Years: If a year is expressed by spelling rather than digits, it is first bisected at the hundreds place into two separate digits, and then those are spelled out. For example, 1984 is split into 19 and 84, and is then spelled as nineteen eighty-four, not one thousand, nine hundred eighty-four.
Decades and centuries: If these are spelled out, lowercase letters are always used (the sixties, the eighteenth century)
Numbers in dialogue: When a character speaks a number in their story dialogue, each digit is spelled out and connected by a hyphen. For example, Barry enunciated the address slowly. "Thirteen-five-oh-nine Broadway. Is that downtown?" This is the only time decimals are spelled: "There is a point-zero-three-five percent chance of statistical error," Rodney said, confirming the panel's worst fears.
When a Numeral Is Needed
NAMES
Some people, like Elizabeth II and 2chanz, have numbers in their name. Preserve these numbers in your writing. Numbers that show a lineage, like Winston Howell III, should always be in capitalized Roman numerals. They should never have Arabic numbers (Winston Howell 9), and only spell these numbers out (with a capital) if the word the is added (Winston Howell the Third).
DATES
While months of the year should always be spelled out and never abbreviated, it is rare to see the day or year spelled out. There are two ways to format a date: the American way (March 22, 2003) and the European way (22 March 2003). MLA requires European style dates in its headers and citations. When using a date in the middle of a sentence, a comma comes after the year when using the American style (He knew that May 13, 2000, was her birthday) but not when using the European style (He knew that 13 May 2000 was her birthday).
Years should never contain commas. If an era is appended to the year, it is separated from the time by a space, uses uppercase letters, and does not use periods--BC (Before Christ), BCE (Before Common Era), and CE (Common Era) follow the year, while AD (Anno Domini) and AH (Anno Hegirae) come before the year: 23 BCE, AD 423, c. 400 BC, AH 950. For a range of years, separate using a dash (not a hyphen): 1801--1872. Years are pluralized into decades and centuries by adding -s without an apostrophe (the 1800s, the psychedelic '60s).
TIMES
While some units of time may be spelled out by writers (two o'clock, thirty seconds, half an hour, quarter to five), times are usually expressed using digits. Times of day are written with the hour and minute divided by a colon (10:30 a.m., 4:43 p.m., 23:00 EST). If a.m. or p.m. are appended to the time, they are separated from the time by a space, use lowercase letters, and use periods. If a time zone is appended to the time, it is separated from the time by a space, uses uppercase letters, and does not use periods.
Amounts of time, such as the length of an audio and video recording, have four divisions using colons for days, hours, minutes, and seconds (4:02:43:03). If there are no additional seconds, you must still show the measurement (2:43:00). However, if the time is, say, only three minutes and three seconds, you can cut the previous digits (3:03).
PAGES
Pages are always expressed as digits, especially in source citations. To indicate that a digit is a page number, it should come after a lowercase p with a period and a space: p. 6 is page six. For a range of pages, use two p's and connect the range with a dash (not a hyphen): pp. 164--78 (notice that the extra 1 was dropped from the second page number for the sake of simplicity). Page numbers also never use commas (p. 1375).
MATHEMATICS
As math has its own grammar and order of operations, mathematical equations and functions should always be expressed with digits: x = 47y + 2(13-y) is a lot easier to understand than x equals forty-seven times y plus the product of two and thirteen minus y. Decimals, precents, probability, and other complex mathematical concepts should stay in the realm of digits.
MONEY
Except for specific references to the currency itself (Lincoln is on the penny and five dollar bill), monetary amounts are always expressed as digits with the symbol of currency included. In America, $ is used for the word dollars and comes before the monetary amount, which can express cents to the dollar using a decimal: $32,150.42. Since $ stands for dollars, the word dollars should not follow the amount.
IDENTIFICATION NUMBERS
Personal identification numbers like phone numbers, account numbers, Social Security numbers, and the like are never spelled but are always expressed as digits. These digits also never use commas but may have their own conventions for being divided by hyphens or parentheticals: for example, phone numbers like 867-5309 divide after the first three digits.
The same goes for location identification numbers tied to places like addresses, room numbers, GPS coordinates, and zip codes. Street names will sometimes come with the suffix -st, -nd, -rd, or -th, like in 1183 42nd Street--these suffixes are never put in smaller superscript text. Addresses never use commas between digits.
SOURCE FORMATING
Alfred Hitchcock directed a film named The 39 Steps, and George Saunders wrote a collection of stories called Tenth of December. These stylistic choices must be retained by a writer wanting to cite these works: they cannot rephrases these titles as The Thirty-Nine Steps or 10th of December. Even if it violates MLA number conventions, the way a source formats their numbers must be maintained by writers.
Some people, like Elizabeth II and 2chanz, have numbers in their name. Preserve these numbers in your writing. Numbers that show a lineage, like Winston Howell III, should always be in capitalized Roman numerals. They should never have Arabic numbers (Winston Howell 9), and only spell these numbers out (with a capital) if the word the is added (Winston Howell the Third).
DATES
While months of the year should always be spelled out and never abbreviated, it is rare to see the day or year spelled out. There are two ways to format a date: the American way (March 22, 2003) and the European way (22 March 2003). MLA requires European style dates in its headers and citations. When using a date in the middle of a sentence, a comma comes after the year when using the American style (He knew that May 13, 2000, was her birthday) but not when using the European style (He knew that 13 May 2000 was her birthday).
Years should never contain commas. If an era is appended to the year, it is separated from the time by a space, uses uppercase letters, and does not use periods--BC (Before Christ), BCE (Before Common Era), and CE (Common Era) follow the year, while AD (Anno Domini) and AH (Anno Hegirae) come before the year: 23 BCE, AD 423, c. 400 BC, AH 950. For a range of years, separate using a dash (not a hyphen): 1801--1872. Years are pluralized into decades and centuries by adding -s without an apostrophe (the 1800s, the psychedelic '60s).
TIMES
While some units of time may be spelled out by writers (two o'clock, thirty seconds, half an hour, quarter to five), times are usually expressed using digits. Times of day are written with the hour and minute divided by a colon (10:30 a.m., 4:43 p.m., 23:00 EST). If a.m. or p.m. are appended to the time, they are separated from the time by a space, use lowercase letters, and use periods. If a time zone is appended to the time, it is separated from the time by a space, uses uppercase letters, and does not use periods.
Amounts of time, such as the length of an audio and video recording, have four divisions using colons for days, hours, minutes, and seconds (4:02:43:03). If there are no additional seconds, you must still show the measurement (2:43:00). However, if the time is, say, only three minutes and three seconds, you can cut the previous digits (3:03).
PAGES
Pages are always expressed as digits, especially in source citations. To indicate that a digit is a page number, it should come after a lowercase p with a period and a space: p. 6 is page six. For a range of pages, use two p's and connect the range with a dash (not a hyphen): pp. 164--78 (notice that the extra 1 was dropped from the second page number for the sake of simplicity). Page numbers also never use commas (p. 1375).
MATHEMATICS
As math has its own grammar and order of operations, mathematical equations and functions should always be expressed with digits: x = 47y + 2(13-y) is a lot easier to understand than x equals forty-seven times y plus the product of two and thirteen minus y. Decimals, precents, probability, and other complex mathematical concepts should stay in the realm of digits.
MONEY
Except for specific references to the currency itself (Lincoln is on the penny and five dollar bill), monetary amounts are always expressed as digits with the symbol of currency included. In America, $ is used for the word dollars and comes before the monetary amount, which can express cents to the dollar using a decimal: $32,150.42. Since $ stands for dollars, the word dollars should not follow the amount.
IDENTIFICATION NUMBERS
Personal identification numbers like phone numbers, account numbers, Social Security numbers, and the like are never spelled but are always expressed as digits. These digits also never use commas but may have their own conventions for being divided by hyphens or parentheticals: for example, phone numbers like 867-5309 divide after the first three digits.
The same goes for location identification numbers tied to places like addresses, room numbers, GPS coordinates, and zip codes. Street names will sometimes come with the suffix -st, -nd, -rd, or -th, like in 1183 42nd Street--these suffixes are never put in smaller superscript text. Addresses never use commas between digits.
SOURCE FORMATING
Alfred Hitchcock directed a film named The 39 Steps, and George Saunders wrote a collection of stories called Tenth of December. These stylistic choices must be retained by a writer wanting to cite these works: they cannot rephrases these titles as The Thirty-Nine Steps or 10th of December. Even if it violates MLA number conventions, the way a source formats their numbers must be maintained by writers.
Page last updated 16 March 2024.
Further Reading
"Numbers [2.126]." MLA Handbook. 9th ed., The Modern Language Association of America, 2021, pp. 82--88.