Researchers at Lab 42 asked 500 LinkedIn users that question and many more, and came up with a variety of answers in this infographic. Among the fun facts they uncovered: We found it interesting the way top level executives use the service in vastly different ways from entry-level workers.
BCE stands for  Before the common era . BC means  Before Christ,  or  Before the Messiah.  Both measure the number of years before the approximate birthday of Yeshua/Jesus. Designation of a year in BC and BCE also have identical values. Many people assume that Yeshua/Jesus was born at the end of 1 BCE.
CE stands for Clear Entry - it is supposed to be used to clear (blank out or return to null) only the thing you are currently typing into the calculator, before you have performed any operation on it. (You realize that you forgot to put the decimal before the 5 in the last entry). Starting over would be a major pain.