What's the difference between 'C' and 'CE' on calculators? While researching this question, we happened upon a word that made us feel old: vintage. It's hard to believe that our trusty math buddy is now considered vintage machinery. According to Vintage Technology, both buttons are a way to clear or cancel an entry. The C button will clear all input to the calculator. The CE button clears the most recent entry, so if you make a mistake in a long computation, you don't need to start all over again. Exactly when calculators began to use these buttons is hard to say.