I've had 2 new HP 12C units fail on me in the last couple years. The display either shows only the error message "Pr - Error", or it fails to clear a previous result (displaying "7.00", for example, no matter how often you try to clear the display). I've been familiar with how to use this model since learning it in the 1990s, but the quality of manufacture has declined. These are junk now and I won't be sending any more money to HP. They ruined a respected brand. What a shame.