YOU SAID:

Yeah! I didnt know that!

INTO JAPANESE

うん！それは知りませんでした！

BACK INTO ENGLISH

Yeah! I did not know that!

INTO JAPANESE

うん！それは知らなかった！

BACK INTO ENGLISH

Yeah! I do not know that!

INTO JAPANESE

うん！そんなことは分かりません！

BACK INTO ENGLISH

Yeah! I don't know!

INTO JAPANESE

うん！わからない！

BACK INTO ENGLISH

Yeah! I don't know!