"Nie mamy wąskich biurek."

Translation: We do not have narrow desks.

[tenkrissirknet]

Is biurek plural?

[ngfio]

Yes (the nominative of plural is "biurka", "biurek" is the genitive of plural), in singular it would be "Nie mamy wąskiego biurka" = "We don't have a narrow desk".

[ADJD4]

Why was 'desks' also given as a translation for 'wąskich'? Is 'wąska' so commonly used to refer to a biurka that you can use it on its own in Polish as an abbreviation of 'wąska biurka', or was this just a technical glitch?

[Jellei]

Definitely a mistake ;) Fixed now.

"biurko" is neuter. It's "wąskie biurko". in singular and "wąskie biurka" in plural.

[RobinB896941]

As a native English speaker, I consider that the more natural translations
"We haven't any narrow desks."
and
"We have no narrow desks."
should be accepted as correct.

Duolingo rejects both, insisting on "got":
"We haven't got narrow desks." (OK as colloquial English)
and
"We have not got narrow desks." (unnaturally stilted).

[Jellei]

Sure thing, added both.