Learn German: Das Hotel hat fünfzehn Zimmer. - The hotel has fifteen rooms.

fünfzehn is literally "five-ten". Just like in English where "fifteen" combines five and ten, German puts fünf (five) and zehn (ten) together. This simple pattern is used for almost all numbers between 13 and 19 (like vierzehn for 14).

Why is the plural just Zimmer and not "Zimmers"?

In German, many nouns ending in -er (like das Zimmer) don't change their spelling when they become plural. So, ein Zimmer is "one room", and fünfzehn Zimmer is "fifteen rooms". You know it's plural here because of the number fünfzehn.

Why is the verb hat instead of haben?

Because Das Hotel acts as an "it" (a single thing). The verb haben (to have) is slightly irregular. For "he", "she", or "it" (er, sie, es), the correct form is hat. So, "The hotel has" is Das Hotel hat.

Why does the sentence use Das for the hotel?

Hotel is a neuter noun in German, so it uses the neuter word for "the", which is das. A helpful tip: many modern words borrowed into German from other languages (like das Hotel or das Restaurant) are neuter.