- There are seven days in the week. [Adjective.]
- Twelve make a dozen. [Noun.]
- I have called twice. [Adverb.]
205. The chief classes of numerals are cardinals and ordinals.
1. Cardinal numeral adjectives (one, two, three, four, etc.) are used in counting, and answer the question “How many?”
- I had to pay three dollars.
- There were forty-two vessels in the fleet.
Note. In such expressions as “The boy was sixteen,” the numeral is a predicate adjective limiting boy ([§ 172, 3]). We need not expand sixteen to “sixteen years old.”
2. Ordinal numeral adjectives (first, second, third, etc.) denote the position or order of a person or thing in a series.
- Carl plays the second violin.
- Your friend is sitting in the fifth row.
206. All the cardinal and ordinal numerals may become nouns and may take a plural ending in some of their senses.
- One is enough.
- Four are missing.
- The nine played an excellent game.
- Three twos are six.
- The men formed by fours.
- Thousands perished by the way.
- Eight is two thirds of twelve. [So regularly in fractional parts.]
Note. Hundred, thousand, million were originally nouns, but are now equally common as adjectives. Other numeral nouns are:—twain, couple, pair, brace, trio, quartette, quintette, foursome, dozen, score, century.