I'm playing Beethoven's Moonlight Sonata and I'm at a part where there's an F double-sharp. Since F is already # in the key signature, do I go to G# or do I start at F and go to G?
Thanks in advance.

I think you go to G because if you had a # and when you have a X (double sharp), if you add them together you get a triple sharp!!

What I'm saying is you would start at the normal note F all the time. The key signature tells you to make it a sharp all the time UNLESS STATED. This double sharp cancels out the original sharp and replaces it with a G.

hey i have a question
the part when it changes to bass cleff for right hand. how should i play it? i mean where is the middle C?
in the 35th interval the first note in an F and it is sharped (not double sharped) but it was already sharped in the key signature what should i play? is this a mistake?

In the bass clef, the middle C is one ledger line above the staff. As to the F sharp, look and see if there was an F natural before it, and you are supposed to go back to f sharp, or something like that.

I hope you can follow that.

thank you very much for the answer.
This is the part i have trouble.
http://img160.imageshack.us/img160/7135/dibujoxi9.jpg

I believe it is F# because earlier in the music the same thing happens with G# in the bass(# on the note;# in key sig.) if you get this, good luck!