die Hausnummer
house number
The number that a building has on a street for identification.
Können Sie mir bitte Ihre Straße und Hausnummer geben?
Could you please give me your street and house number?

house number
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house number
The number that a building has on a street for identification.
Können Sie mir bitte Ihre Straße und Hausnummer geben?
Could you please give me your street and house number?

The word is made up of 'Haus' (house) and 'Nummer' (number). The 's' in between is a linking s that connects the two words. Literally, it is the number of a house.
Die Hausnummer 10 befindet sich auf der anderen Straßenseite.
House number 10 is on the other side of the street.
In the context of addresses, 'Hausnummer' (house number) is almost always mentioned together with the street. The typical question is: 'Wie ist Ihre Straße und Hausnummer?' (What is your street and house number?).
Bitte geben Sie bei der Bestellung Ihre vollständige Adresse mit Straße und Hausnummer an.
Please provide your full address, including street and house number, when ordering.
The second meaning is used only colloquially to comment on a surprisingly high number, usually a price. It expresses astonishment or even admiration.
10.000 Euro für ein Fahrrad? Das ist eine echte Hausnummer.
10,000 euros for a bicycle? That's a really large number.
In the colloquial meaning, the word is often used in the fixed expression 'Das ist (mal) eine Hausnummer!' (That's quite something / that's a big number!). It functions as a commenting exclamation.
Er will 50 Kilometer am Stück laufen. Das ist mal eine Hausnummer!
He wants to run 50 kilometers in one go. That's quite something!
address
'die Adresse' and 'die Hausnummer' often belong together, but they do not refer to the same thing. The address is the full location information, for example street, house number, postal code, and city. The house number is only one part of it: the number of a building on a street. The words can be confused because both are important for finding a house. If someone asks for the address, the house number alone is not enough. If only the number on the house is missing, you ask more specifically for the 'Hausnummer'.

Vor dem Termin prüft ihr die Hausnummer noch einmal auf der Einladung.
Before the appointment, you check the house number on the invitation once more.
Beim Arzt muss sie ihre neue Adresse angeben.
At the doctor's office, she has to provide her new address.