Formal:
* बहुत बहुत धन्यवाद (Bahut bahut dhanyavaad): This is the most common and formal way to say "Thank you very much." It literally translates to "Many many thanks."
* आपका बहुत-बहुत धन्यवाद (Aapka bahut-bahut dhanyavaad): This is also a formal way to say "Thank you very much," but it includes "your" before the thanks, making it slightly more polite.
Informal:
* बहुत-बहुत शुक्रिया (Bahut-bahut shukriya): This is a more informal way to say "Thank you very much." It's still polite, but it's more commonly used among friends and family.
* बहुत धन्यवाद (Bahut dhanyavaad): This is another informal way to say "Thank you very much." It's a more shortened version of the formal phrase.
Other options:
* आपका बहुत-बहुत आभार (Aapka bahut-bahut aabhaar): This is a more formal and poetic way to say "Thank you very much."
* आपकी कृपा (Aapki kripa): This is a very formal and polite way to say "Thank you very much," literally meaning "Your kindness."
Ultimately, the best way to say "Thank you very much" in Hindi will depend on the specific situation and your relationship with the person you are speaking to.