is this そうなんだか a valid sentence?


If そうなんですか (sounandesuka) is formal, how come it's not often that I hear of
そうなんだか (sounandaka) as casual version or maybe that I just don't hear enough?
thanks.




Because speaking casually very often means discarding the question mark か as
well, making the casual version of そうなんですか？ -> そうなんだ？ It's just not そうなんだか,
but "だか" that you wouldn't hear in any sentence, because you would simply stop
at だ。




Because speaking casually very often means discarding the question mark か as
well, making the casual version of そうなんですか？ -> そうなんだ？ It's just not そうなんだか,
but "だか" that you wouldn't hear in any sentence, because you would simply stop
at だ。

