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# Ordinal number

An **ordinal number** /ˈɔ:(r).də.nəl ˈnʌm.bə(r)/ is a number that is used to describe a set of objects in order, as in a sequence or list. For example, in English, *first*, *fourth* and *sixteenth*.

Contrast cardinal number.

## Meaning[edit | edit source]

The ordinal numbers represent natural numbers, i.e. positive integers beginning with 1, i.e. 1, 2, 3, etc.

*first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth, nineteenth, twentieth, twenty-first, twenty-second, twenty-third*, etc.

Ordinal numbers can’t usually be negative, and they can’t be fractions. In computing, sometimes 0th (*zeroth*) is used, as computers need to handle the number 0.

## Usage[edit | edit source]

Ordinal numbers are generally used as adjectives, which may then be zero-nominalised.

Ordinal numbers are used in various ways, including being used:

- To refer to items in a sequence or list, e.g.
*the first one*,*the second one*etc.- To refer to items directly with zero-nominalisation, e.g.
*the first*,*the second*, etc.

- To refer to items directly with zero-nominalisation, e.g.
- As sequencing adverbs;
*first open the packet, second pour the contents into a tray…* - To form the denominator of vulgar fraction, e.g. 1/8 =
*one*. But note that 1/2 has its own word,__eighth__*half*rather than **one second*. - To mark dates, e.g.
*the 6th of July*.

Special Latinate ordinal numbers are used in some contexts.

## Pronunciation[edit | edit source]

Students have the usual problems with the dental fricatives.

## Orthography[edit | edit source]

In English, ordinal numbers are typically written as an Arabic numeral in base 10, plus a suffix. The default suffix is *ordinal -th*, e.g. *4th, 5th, 6th*. However, this only applies to numbers that are pronounced ending in *-th*. So, *first* becomes *1st*, *second* becomes *2nd*, and *third* becomes *3rd*. Other numbers ending in 1, 2 or 3 also follow this pattern, e.g. *21st, 43rd, 52nd* except for those ending *11*, *12* or *13*, which take *-th*. This may use superscript, particularly after Microsoft Word enabled this; e.g. 1^{st} 2^{nd}, although this is discouraged by some style guides.

In the names of monarchs, Roman numerals are used, and are read as "the nth,” e.g. *George VI* is read as “George the Sixth.”

## Pedagogy[edit | edit source]

Ordinal numbers are usually first encountered by students with regard to dates, for which they will need ordinal numbers up to thirty-first.

Regular ordinal numbers end in -th; irregular ordinal numbers are the first, second, third. Students may over-regularise these and say e.g. *"oneth,” *"twoth,” *"threeth,” possibly with a 10x number as well, e.g. *"twenty-twoth.”

Students often struggle with the /θ/ sound.

When reading names of monarchs, students will often misread the numeral, e.g. *George IV* (“George the Fourth") becomes *“George four" or *“George Ivy.”