English numerals

English number words include numerals and various words derived from them, as well as a large number of words borrowed from other languages.
Cardinal numbers.
Cardinal numbers refer to the size of a group. In English, these words are numerals.
If a number is in the range 21 to 99, and the second digit is not zero, the number is typically written as two words separated by a hyphen.
In English, the hundreds are perfectly regular, except that the word "hundred" remains in its singular form regardless of the number preceding it.
So too are the thousands, with the number of thousands followed by the word "thousand". For the number one thousand it may be written 1 000 or 1000 or 1,000, for larger numbers they are written for example 10 000 or 10,000 for ease of human reading. The use of the , as a separator is avoided in some languages as it is used for a decimal placement, for example with money. As a result some style guides recommend avoidance of the , as a separator and only to use the . as a decimal placement. Thus a half would be written 0.5 in decimal, base ten notation, and fifty thousand as 50 000, and not 50.000 nor 50,000 nor 50000. As the English language has no language academy to make usage correct there is still a wide variety of usage, other languages do have language academies which ruled on these matters, yet their rulings are deprecated by international standards like the SI system or EU recommendations which lead to varied usage.
In American usage, four-digit numbers are often named using multiples of "hundred" and combined with tens and ones: "eleven hundred three", "twelve hundred twenty-five", "four thousand forty-two", or "ninety-nine hundred ninety-nine." In British usage, this style is common for multiples of 100 between 1,000 and 2,000 (e.g. 1,500 as "fifteen hundred") but not for higher numbers.
Americans may pronounce four-digit numbers with non-zero tens and ones as pairs of two-digit numbers without saying "hundred" and inserting "oh" for zero tens: "twenty-six fifty-nine" or "forty-one oh five". This usage probably evolved from the distinctive usage for years; "nineteen-eighty-one", or from four-digit numbers used in the American telephone numbering system which were originally two letters followed by a number followed by a four-digit number, later by a three-digit number followed by the four-digit number. It is avoided for numbers less than 2500 if the context may mean confusion with time of day: "ten ten" or "twelve oh four".
Intermediate numbers are read differently depending on their use. Their typical naming occurs when the numbers are used for counting. Another way is for when they are used as labels. The second column method is used much more often in American English than British English. The third column is used in British English but rarely in American English (although the use of the second and third columns is not necessarily directly interchangeable between the two regional variants). In other words, British English and American English can seemingly agree, but it depends on a specific situation (in this example, bus numbers).
Note: When a cheque (or "check") is written, the number 100 is always written "one hundred". It is never "a hundred".
In American English, many students are taught, not to use the word "and" anywhere in the whole part of a number, so it is not used before the tens and ones. It is instead used as a verbal delimiter when dealing with compound numbers. Thus, instead of "three hundred and seventy-three," "three hundred seventy-three" would be said. Despite this rule, some Americans use the "and" in reading numbers containing tens and ones as an alternative variant.
Very large numbers.
For numbers above a million, three main systems name numbers in English (for the use of prefixes such as kilo- for a thousand, mega- for a million, milli- for a thousandth, etc. see SI units):
Many people have no direct experience of manipulating numbers this large, and many non-American readers may interpret "billion" as 1012 (even if they are young enough to have been taught otherwise at school); moreover, usage of the "long" billion is standard in some non-English speaking countries. For these reasons, defining the word may be advisable when writing for the public.
The numbers past one trillion in the short scale, in ascending powers of 1000, are as follows: quadrillion, quintillion, sextillion, septillion, octillion, nonillion, decillion, undecillion, duodecillion, tredecillion, quattuordecillion, quindecillion, sexdecillion, septendecillion, octodecillion, novemdecillion and vigintillion (which is 10 to the 63rd power, or a one followed by 63 zeros). The highest number in this series listed in modern dictionaries is centillion, which is 10 to the 303rd power. The interim powers of one thousand between vigintillion and centillion do not have standardized names, nor do any higher powers, but there are many extensions in use. The highest number listed in Robert Munafo's table of such unofficial names is milli-millillion, which was coined as a name for 10 to the 3,000,003rd power.
The googolplex was often cited as the largest named number in English. If a googol is ten to the one hundredth power, then a googolplex is one followed by a googol of zeros (that is, ten to the power of a googol). There is the coinage, of very little use, of ten to the googolplex power, of the word googolplexplex.
The terms "arab", "kharab", "padm" and "shankh" are more commonly found in old books on Indian mathematics.
Here are some approximate composite large numbers in American English:
Often, large numbers are written with (preferably non-breaking) half-spaces or thin spaces separating the thousands (and, sometimes, with normal spaces or apostrophes) instead of commas—to ensure that confusion is not caused in countries where a decimal comma is used. Thus, a million is often written 1 000 000.
In some areas, a point (. or ·) may also be used as a thousands separator, but then the decimal separator must be a comma (,). In English the point (.) is used as the decimal separator, and the comma (,) as the thousands separator.
Special names.
Some numbers have special names in addition to their regular names, most depending on context.
Combinations of numbers in most sports scores are read as in the following examples:
Naming conventions of Tennis scores (and related sports) are different from other sports.
The centuries of Italian culture have names in English borrowed from Italian: 
When reading numbers in a sequence, such as a telephone or serial number, British people will usually use the terms "double" followed by the repeated number. Hence 007 is "double oh seven". Exceptions are the emergency telephone number 999, which is always "nine nine nine" and the apocalyptic "Number of the Beast", which is always "six six six". In the US, 911 (the US emergency telephone number) is usually read "nine one one", while 9/11 (in reference to the September 11, 2001, attacks) is usually read "nine eleven".
Multiplicative adverbs and adjectives.
A few numbers have specialised multiplicative numbers (adverbs), which express how many times some event happens:
Compare these specialist multiplicative numbers to express how many times some thing exists (adjectives):
English also has some multipliers and distributive numbers, such as "singly".
Other examples are given in the Specialist Numbers.
Negative numbers.
The name of a negative number is the name of the corresponding positive number preceded by "minus" or (American English) "negative". Thus −5.2 is "minus five point two" or "negative five point two". For temperatures, North Americans colloquially say "below"—short for "below zero"—so a temperature of −5° is "five below" (in contrast, for example, to "two above" for 2°). This is occasionally used for emphasis when referring to several temperatures or ranges both positive and negative. This is particularly common in Canada where the use of Celsius in weather forecasting means that temperatures can regularly drift above and below zero at certain times of year.
Ordinal numbers.
Ordinal numbers refer to a position in a series. Common ordinals include:
"Zeroth" only has a meaning when counting starts with zero, which happens in a mathematical or computer science context. Ordinal numbers predate the invention of zero and positional notation.
Ordinal numbers such as 21st, 33rd, etc., are formed by combining a "cardinal" ten with an "ordinal" unit.
Higher ordinals are not often written in words, unless they are round numbers (thousandth, millionth, billionth). They are written with digits and letters as described below. Some rules should be borne in mind.
These ordinal abbreviations are actually hybrid contractions of a numeral and a word. 1st is "1" + "st" from "first". Similarly, "nd" is used for "second" and "rd" for "third". In the legal field and in some older publications, the ordinal abbreviation for "second" and "third" is simply "d".
NB: "D" still often denotes "second" and "third" in the numeric designations of units in the US armed forces, for example, 533d Squadron, and in legal citations for the second and third series of case reporters.
Dates.
There are a number of ways to read years. The following table offers a list of valid pronunciations and alternate pronunciations for any given year of the Gregorian calendar.
"Twelve thirty-four" would be the norm on both sides of the Atlantic for the year 1234. The years 2000 to 2009 are most often read as "two thousand", "two thousand (and) one" and the like by both British and American speakers. For years after 2009, "twenty eleven", "twenty fourteen", etc. are more common, even in years earlier than 2009 BC/BCE. Likewise, the years after 1009 (until 1099) are also read in the same manner (e.g. 1015 is either "ten fifteen" or, rarely, "one thousand fifteen"). Some Britons read years within the 1000s to 9000s BC/BCE in the American manner, that is, 1234 BC is read as "twelve (hundred and) thirty-four" BC, while 2400 BC can be read as either "two thousand four hundred" or "twenty four hundred" BC.
Fractions and decimals.
In spoken English, ordinal numbers also quantify the denominator of a fraction. Thus "fifth" can mean the element between fourth and sixth, or the fraction created by dividing the unit into five pieces. In this usage, the ordinal numbers can be pluralized: one seventh, two "sevenths." The sole exception to this rule is division by two: the ordinal term "second" can only refer to location in a series; for fractions English speakers use the term "half" (plural "halves").
Here are some common English fractions (known linguistically as "partitive numerals"):
Alternatively, and for greater numbers, one may say for 1/2 "one over two", for 5/8 "five over eight", and so on. This "over" form is also widely used in mathematics.
Fractions together with an integer are read as follows:
A space is required between the whole number and the fraction; however, if a special fraction character is used like "½", then the space can be done without, e.g.
Numbers with a decimal point may be read as a cardinal number, then "and", then another cardinal number followed by an indication of the significance of the second cardinal number (mainly U.S.); or as a cardinal number, followed by "point", and then by the digits of the fractional part. The indication of significance takes the form of the denominator of the fraction indicating division by the smallest power of ten larger than the second cardinal. This is modified when the first cardinal is zero, in which case neither the zero nor the "and" is pronounced, but the zero is optional in the "point" form of the fraction.
Some American and Canadian schools teach students to pronounce decimally written fractions (for example, ".5") as though they were longhand fractions ("five tenths"), such as "thirteen and seven tenths" for 13.7. This formality is often dropped in common speech and is steadily disappearing in instruction in mathematics and science as well as in international American schools. In the U.K., and among most North Americans, 13.7 would be read "thirteen point seven".
For example:
In English the decimal point was originally printed in the center of the line (0·002), but with the advent of the typewriter it was placed at the bottom of the line, so that a single key could be used as a full stop/period and as a decimal point. In many non-English languages a full-stop/period at the bottom of the line is used as a thousands separator with a comma being used as the decimal point.
Whether or not digits or words are used.
With few exceptions, most grammatical texts rule that the numbers zero to nine inclusive should be "written out" – instead of "1" and "2", one would write "one" and "two".
After "nine", one can head straight back into the 10, 11, 12, etc., although some write out the numbers until "twelve".
Another common usage is to write out any number that can be expressed as one or two words, and use figures otherwise.
Numbers at the beginning of a sentence should also be written out, or the sentence rephrased.
The above rules are not always followed. In literature, larger numbers might be spelled out. On the other hand, digits might be more commonly used in technical or financial articles, where many figures are discussed. In particular, the two different forms should not be used for figures that serve the same purpose; for example, it is inelegant to write, "Between day twelve and day 15 of the study, the population doubled."
Empty numbers.
Colloquial English's small vocabulary of empty numbers can be employed when there is uncertainty as to the precise number to use, but it is desirable to define a general range: specifically, the terms "umpteen", "umpty", and "zillion". These are derived etymologically from the range affixes:
The prefix "ump-" is added to the first two suffixes to produce the empty numbers "umpteen" and "umpty": it is of uncertain origin. A noticeable absence of an empty number is in the hundreds range.
Usage of empty numbers:
See also Placeholder name.