How do you say Thank very much in welsh?

There are a few ways to say "Thank you very much" in Welsh, depending on the level of formality and emphasis you want to convey:

Formal:

* Diolch yn fawr iawn: This is the most common and formal way to say "Thank you very much".

* Diolch yn fawr iawn i chi: This is similar to the above, but adds "to you" at the end, making it more polite.

Informal:

* Diolch yn fawr: This is a more casual way to say "Thank you very much".

* Diolch o galon: This literally means "Thank you from the heart", and expresses a deeper gratitude.

Even more informal:

* Diolch: This simply means "Thank you", and can be used in very casual settings.

The best way to choose the right phrase depends on the context and your relationship with the person you're speaking to.