I have tried to protect a spreadsheet with a 252 character password made up
of Numbers, UCase, LCase and various Symbols. I know it works because if I
change just one character somewhere in that string, the sheet fails to
unprotect. I then sent it to a friend to see if he could break it. He said
it took less than 2 minutes with a commericial product and it came up with a
working unprotect password only 12 characters long (all UCase Letters and a
sequence not found in the 252 one).

How is it possible for a 12 character password to unlock a 252 one ????