Numbers as Adjectives

A subscriber recently wrote in with a question that’s a good followup to last week’s Tip of the Week, Writing Numbers:

“When are hyphens used with numbers? Is it 13 feet or 13-feet; 12 hours or 12-hours?”

Rule: Generally, hyphenate between two or more adjectives when they come before a noun and act as a single idea.

This rule can also be applied when a number and a measurement unit taken together form an adjective, that is, when they describe another object.

Examples:
A 22-inch monitor is too big for my desk.
Nurses work 12-hour shifts.
Anthony swung his five-pound hammer.
In the previous sentences, the measurements, such as 22-inch, describe specific objects, such as monitor.

When measurements are not acting as adjectives, hyphens are not needed.

Examples:
Suzanne won the race by 25 yards.
Twelve hours later, she was exhausted.
Anthony’s hammer weighs five pounds.

Pop Quiz: Choose A or B.

1. A. I can’t believe she wrote a 33-page treatise on how to screw in a light bulb.
1. B. I can’t believe she wrote a 33 page treatise on how to screw in a light bulb.

2. A. I can’t believe she wrote 33-pages on how to screw in a light bulb.
2. B. I can’t believe she wrote 33 pages on how to screw in a light bulb.

3. A. Harold found a 110-year-old book at the flea market.
3. B. Harold found a 110 year old book at the flea market.

4. A. Harold found a book that must have been 110-years-old at the flea market.
4. B. Harold found a book that must have been 110 years old at the flea market.

Answers

1. A.
2. B.
3. A.
4. B.