Maurice Janssen Satan's Calculator Trick

Display Satan's number 666 on a calculator. (Use a phone's calculator.) Slowly turn the phone upside down, but miraculously the number still reads 666. Best to watch the demo video below.
            
            
                no apps required
                set up takes literally two seconds
                phone can be borrowed
                virtually impromptu, no body else needed
                no screen shot switches, no toxic force
                no memory recall buttons to push
            
            1st edition 2019, 2 pages.