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.
Posted on Thursday, March 5th, 2009 at 4:07 pm

Hi. I recently was asked by a friend, “when can you use “I IS”"? I said never. He said there is an instance, is this true? And if so, when???
You’re right. You can never use “I is.”
My daughter’s school has this practice of asking the pupils to clap their hands once and then keep quiet. Some teachers do it by saying “Give me a silent clap.” while others say “Give me a silence clap.” Should it be a ‘silence clap’ or a ‘silent clap’? How do I explain to my daughter?
Actually, neither expression makes much sense and would be called an oxymoron. But if you have to choose, then “silent clap” because “silent” is an adjective describing “clap” while “silence” is a noun.
Hi, I have a doubt..when I use the numbers as adjectives, I can say “a one-week trip” for exemple, but why do I use the article a instead an, because one begins in vowel…could you help me? thanks
This is from the GrammarBook.com site on a vs. an:
a vs. an
Rule. Use a when the first letter of the word following has the sound of a consonant. Keep in mind that some vowels sound like consonants when they’re sounded out as individual letters.
Examples:
* a finger
* a hotel
* a U-turn (pronounced You-turn)
* a HUD program
* a NASA study
Rule. Use an when the first letter of the word following has the sound of a vowel. Remember that some consonants sound like vowels when they’re spoken as individual letters.
Examples:
* an FBI case (F is pronounced ef here)
* an honor (H is silent here)
* an unusual idea
* an HMO plan (H is pronounced aitch here)
* an NAACP convention (N is pronounced en here)
Deciding whether to use a or an before abbreviations can be tricky. The abbreviation for Frequently Asked Questions (FAQ) causes confusion because it can be pronounced as a word (fak), or one letter at a time (F-A-Q). Using the guidelines above, one would say a FAQ when it is pronounced as one word, and an FAQ when it is pronounced one letter at a time.
What is the proper use of a hyphen in fractions? For example: The Trustee shall distribute one-half of the trust to him.
Rule 3 of Writing Numbers is, “Always spell out simple fractions and use hyphens with them.” Your sentence is correct.
Could you please indicate the proper way to include the measurement in this sentence? Always have the proper adjustment of 1/8th inch.
Always have the proper adjustment of one-eighth inch.
thank you! your explanations have helped me a lot!
You are welcome. And if you do not mind one more bit of help, don’t forget your capital letters at the beginning of each sentence!
Hi! Could anyone help me out? Which is correct:
a hundred-thousand-dollar deficit; or
a $100,000.00-deficit
Thanks!
The best way to write this out would be a one-hundred-thousand-dollar deficit.
There are several instances where you can say “I is”, and I am not talking about Ebonics:) Are you ready? Here we go; I is a proper noun. I is the ninth letter in the alphabet. I is a vowel. I is the first letter in the word impressive. Mkay?;)
You are correct; however, Chicago Manual of Style’s Rule (7.58) states, “When a word or term is not used functionally but is referred to as the word or term itself, it is either italicized or enclosed in quotation marks.”
For instance:
I is a proper noun. OR “I” is a proper noun.
Excellent explanation. By the way, and speaking about numbers as adjectives,
what about these expressions?
Two-barreled gun, one-legged man, twin-engine (or twin-engined) (either twin-engine and twin-engined appear in may user-created webpages such wikipedia).
Are they old fashioned? What are they based on and what are they limits?
Thanks from Spain.
Your first two are similar to our examples in the blog “Numbers as Adjectives” and the last if used with a noun such as twin-engine aircraft, is an example of a compound adjective. These are all grammatically correct. Twin-engine aircraft are still common. I’m not an expert on guns, but two-barreled guns were probably more common in the past. “One-legged man” has become a less common expression as medical science has become more adept at fitting people who have lost all or part of a leg with a prosthesis.