Is it me or is it difficult to use the stock calculator app on the iPhone? I always seem to mess up if I'm calculating more than a few numbers! I don't know if I drag my fingers or something? I just don't get it. Thinking of resorting to an old hand held calculator at my work desk. Does any one else have this problem? Any luck with 3rd party apps? I would never think I'd have issues with it but I do.