For the life of us, we can't figure out why anyone other than a rocket scientist would want to install a different version than this free one that comes pre-installed. Windows calculator has two interfaces: an easy one, and a scientific one. So perhaps a rocket scientist could fare well with Windows Calculator after all! Commands are the instructions that a computer follows to perform an action. 2 To make them work inside of a program, programmers assign commands to objects like buttons for example. The commands in a program are pretty useless unless they have some data to act on so programmers either give the programs some data to work with (list of names or numbers for example) or they make the program generate it's own data. One of the easiest and least expensive things you can do to extend the life of your computer is to get rid of unnecessary programs, folders, and files. A disk drive that's clogged with unnecessary and unused files is disk drive that works harder than it has to. Although Window's defrag system can ease some of the stress that these files place onto the drive, it doesn't do much to get rid of the problem in the first place. So if Microsoft Edit was in a directory or folder named "Process," you could start the program by typing, "C:>process\edit.com" Then, and only then would the program load up for use. This is a small command, but just imagine if you had a program that was deeply nested within a series of folder. Sometimes, errors occur because a system doesn't have the required drivers or the drivers that are on the system are the incorrect version. Both errors in these cases can be resolved by updating the computer on a regular basis. Microsoft provides a section on its website that can automatically update a computer online and it does this at no cost in an effort to reduce errors like this. This option may not be available on every device that you encounter, but when it is available, be sure to use it. There's just no way around it. Computers and computerized systems are here to stay. There's no need to fear them - but you surely can't avoid them. Just remember the menu system and you'll soon discover that you can approach and use these things as if you designed them yourself.