I don't even think most high schools indicate GPAs. I know that my high school transcript only has a rank, not a GPA (although I guess you could figure it out, but you'd need your grades from each year--it would be a mess to figure out indeed). I can't believe that any law school would need that information on an application. Perhaps ONE law school asks for it if you know it, which is how it ended up on the common information form??? You probably can leave it blank and then when you print out an application make sure it didn't ask for the HS GPA.