Grammar Tips: Hyphens and ages

Hey all, Robin here. I don't have a blog myself (maybe I need one) so I'm hijacking Michael's. I want to do a series of posts on editing...I'm doing a lot of editing these days and I'm always learning something new and thought I would pass on what I find interesting.

Today, I want to discuss a when you use hyphens in ages. For instance is it "twelve-year-old" or "twelve year old."

The answer depends on if the phrasal adjective comes before or after the noun.  

• When before the noun: use hyphens
• When after the noun: no hyphens

That's all fine and good but I had a bigger problem, what if you are using the phrase as a noun rather than an adjective.  This came up because of the following sentence in Michael's new novel, The Death of Dulgath.

My mother had all the creativity of an eight-year-old with a spotted puppy. 

Well, as it turns out you do hyphenate it.  If you want to learn more on the subject, I recommend this post on the Grammarist site.

Hope it helps someone. If nothing else, it'll provide a nice bookmark for me the next time my old brain can't remember how to handle hyphens and ages.