Optional Plural

[giantantattack.livejournal.com]

Is there a Russian system for dealing with plurals which may or may not occur? For example, in English, on a form someone may write, "I was out of town for ____ day(s)," leaving the option open for the person filling out the form to write in either "one" or "thirty-four" without damaging the grammatical structure of the sentence.

How does one accomplish this in Russian?