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I have searched and searched, but can't find an answer to this question:

I know that the age in the following sentence should be hyphenated the following way:

"A 10-year-old girl went to the park."


But, what about when the noun that 10-year-old modifies is understood?

"A 10-year-old went to the park."

Is that correct? Or should I remove the hyphens because "girl" is not there?

"A 10 year old went to the park?"

I have searched for an answer, but can't find a book that addresses this precisely.

HELP!!!!!!

Looks like typical convention says that 10-year-old is okay. Ex: http://grammar.ccc.commnet.edu/GRAMMAR/compounds.htm (under the first section - hyphenated forms).

You can also circumvent any opportunity for doubt by saying "10-year-old child."

Ed

Thank you!