Hyphens are the grammatical ropes; they link things
together. A hyphen is a short, horizontal line that links words together
(these are different from dashes). The main uses for hyphens are as follows:
1.
To form compound adjectives.
Compound adjectives are multiple
words working together to function as one adjective. Hyphens join these words
together to create a compound adjective.
For example:
The 9-year-old boy already knew
most of the concepts taught in high school.
Here, “9-year-old” is a pair of
words and a number that work together to describe the boy. Therefore, it is a
compound adjective, and hyphens should be used. Refer to the next grade concept
explanations for a full explanation of compound adjectives.
2.
To form certain compound words.
Consider the following example:
The new editor-in-chief of the
famous magazine is extremely pleased with his new job.
In this example, “editor-in-chief”
is a compound word and thus requires hyphens.
3.
In fractions and numbers from 21 to 99.
For example:
Twenty-five people were in Mrs.
Baker’s class, but one-fifth of them switched to another class during the year.
In this example, the first hyphen is
used for a number between 21 and 99, “twenty-five.” The second hyphen separates
the numerator and denominator of the fraction “one-fifth.”