"There are seven days in a week."

Translation: एक हफ़्ते में सात दिन होते हैं।

[Lalremruat13]

Why is it hafte and not hafta?

[GraysonElliott]

The में makes it oblique.

[inbetweener]

Why hote hai and not just hai?

[manimaran_p]

Sentences which convey an univeral truth will have to end like that

eg. एक साल में बारह महीने होते है

[MahaDidi]

Isn't just हफ़्ते में सात दिन होते हैं। ok as well?

[emrys29]

Correct.