見けん当とうがつかない

expression

have no idea; can't even guess

Used when one cannot form even a rough estimate or guess about something. Often implies complete lack of information or clue.

• 彼かれがどこに行いったのか、見けん当とうがつかない。

  I have no idea where he went.

• この問もん題だいの答こたえはまったく見けん当とうがつかない。

  I can't even guess the answer to this problem.