Compound nouns: the last word decides
Wartenummer die
Always In 98.9% of 6,721 common compound nouns, the article comes from the last word.
The last part decides the article: die Nummer, so die Wartenummer.
die Wartenummer
It's die Wartenummer. Wartenummer is feminine, plural die Wartenummern.
Ich habe die Wartenummer 42.
I have queue number 42.
Wartenummer die
Always In 98.9% of 6,721 common compound nouns, the article comes from the last word.
The last part decides the article: die Nummer, so die Wartenummer.