There is movie named "40 year old virgin"
just wondering why it is not "40 yearS old virgin" ?
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do not we say "yearS", when somebody ask us "how old are you?" and we answer ie : 36 yearS old ?
This film is more correctly spelt The 40-Year-Old Virgin (the capitals are used because it's a title).
We say 'I'm 40 years old' or 'I'm a 40-year-old man'.
Rover
When used with numbers, the measurements are in the singular before the noun.
A three-mile walk. A walk of three miles.
A 10-meter diving board. A diving board of 10 meters.
A two-week vacation. A vacation of two weeks.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.