If you want to calculate the sum area of closed linear entities you can use 'paste Total Area'. Select the closed linear entities you want and hit enter. The sum area is shown in an alert and a prompt on the command line. The command places the result on the windows clipboard as well. So if you want to write the result somewhere, for instance in an email or excel document you only have to click on the place where the result should go and you can paste the result straight away.