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Unterschied: Nummer vs. Zahl
Once again I found it hard to find any difference between two nouns (die Zahl and die Nummer).To me they are exactly the same. They both mean number (1, 33, 59 etc.). I also checked on Duden and it gives them as synonymous. Do you know if there is a difference and in case what is it about?
There are indeed slightly different meanings of the word "Zahl":
(1) In can refer to an amount. In that case, "Zahl" can also usually be replaced by "Anzahl".
Example: "Die Zahl/Anzahl der Wartenden war zehn." (Granted, this sentence sounds very formal; "Anzahl" is not often used in daily life. One would rather say: "Es haben zehn Leute gewartet.")
(2) It can refer to an index. In that case, "Zahl" can usually be replaced by "Nummer".
Example: "Auf oeffentlichen Aemtern bekommt man in Warteraeumen eine Nummer/Zahl. Je hoeher die Nummer/Zahl, umso laenger muss man warten bis man bedient wird."
(3) There are cases where "Zahl" is a technical term and should not be replaced.
Example: "Zehn is eine natuerliche Zahl." ("Nummer" would also be understood, but it is very unusual.)
Zahl refers to a number that can be used in calculations — quantities, amounts etc.
Nummer refers to numbers that would not be added or subtracted — house numbers, telephone.
There is an extended discussion at the forum of WordReference.
They usually can be used as synonyms, but there are some cases where it would not be 100% right:
If it refers to an amount, it can be replaced by "Anzahl". Example: Die Zahl (Anzahl) der Schüler in berufsbildenden höheren Schulen steigt. (meaning the amount of students). You can't say the "Nummer der Schüler".
It can refer to an index, where you would say "Nummer" but not "Zahl". Example: Er ist die Nummer 1 auf der Liste der meist prämierten Schauspieler. (meaning he is number one)
So you can say a "Nummer" is a "Zahl" which refers to an order.
Usually "Zahl" is used more often. For example in mathematics, you mostly speak of "Zahlen"
a "Nummer" is a "Zahl" which refers to an order. A Telefonnummer is not a Zahl, its just a sequence of digits, but their combination dont make up a number which refers to an order.
There are cases where you use number, Telefonnummer, Hausnummer. In mathematics you have Zahlen, not numbers: gerade und ungerade Zahlen, Quadratzahlen, X steht für eine gesuchte Zahl in einer Gleichung, die Folge der natürlichen Zahlen.
Wrong number is Falsch verbunden.
More examples in the German-German dictionary of The Free Dictionary
There exists different usage for both words. For instance, Zimmernummer sounds fine, whereas Zimmerzahl does not. Moreover, in mathematics Zahlen refers to a much wider concept: There are complex numbers, p-adic numbers, cardinal numbers; in German komplexe Zahlen, p-adische Zahlen, Kardinalzahlen. One cannot use Nummer in these contexts.
