Formal:
* Nduathi (pronounced "ndoo-athi") - This is a general, polite way to say "I am happy"
* Nduathi mũthemba (pronounced "ndoo-athi moo-them-ba") - This means "I am very happy"
Informal:
* Ndingĩĩ mũthemba (pronounced "nin-gi-i moo-them-ba") - This means "I am very happy" and is a more casual way to say it.
Other variations:
* Ndingĩĩ mũnene (pronounced "nin-gi-i moo-nen-e") - This means "I am very happy" and is a more emphatic way to say it.
* Ndingĩĩ mũnene mũthemba (pronounced "nin-gi-i moo-nen-e moo-them-ba") - This means "I am extremely happy" and is a very strong way to express happiness.
It's important to note that depending on the context and the person you're talking to, you might choose one of these variations over another.