I'll show you the basic usage of IF function in Google Drive Spreadsheet. The IF function returns one value if a specified condition evaluates to TRUE, or another value if it evaluates to FALSE.
If you are using removable disk or USB key then you should look at this lesson. I will show you how you can safely remove your device from computer without the fear of losing data.
A computer is a general purpose device that can be programmed to carry out a finite set of arithmetic or logical operations. Now you can check if you know the history of computers?