With History, so that you are confident that the value is true. Very often, we are not quite sure whether there're miss typing.Smart Calculator:1 List all the past entries, you can check for any error,miss typing...2 you can Use Last calculated Result for next operation.Click on the past history record to popup a dialog of "use Result", click ok. the last result is used as the next operant.3 Big font, to comfort your eyes.---Tips---C: Clear AllArrow: backspace (del last digit)