Informal:
* ज़रूर (zarur): This is the most common and versatile way to say "sure" or "sure thing." It can be used in almost any situation.
* ठीक है (theek hai): This literally means "okay" but is often used as a synonym for "sure."
* बिल्कुल (bilkul): This is a more emphatic way of saying "sure" or "absolutely."
Formal:
* निश्चित रूप से (nishchit roop se): This means "definitely" or "certainly."
* ज़रूर (zarur): Even though "zarur" is informal, it can also be used in formal situations.
Other options:
* कोई बात नहीं (koi baat nahi): This means "no problem" and can be used as a way of saying "sure" in some situations.
* बेशक (beshak): This means "of course" and is a more emphatic way of saying "sure."
The best way to choose the right phrase is to consider the context of the conversation and the level of formality you want to convey.