> A computer, or CPU does not multitask.
Yes it does. http://en.wikipedia.org/wiki/Computer_multitasking
At this point in time my computer is running several simultaneous tasks, not just accepting keyboard input for my browser; it is checking periodically for email without my input, downloading some torrents, indexing my hard drive, keeping track of the time, sorting out memory, maintaining the swap file, and loads of other stuff that wakes up and does its bit all without me noticing.
> A person multitasks when a person uses two or more programs simultaneously (e.g. listening to
music while working on a spreadsheet).
I wouldn't disagree with that. But the computer is also multitasking, because it is running a spreadsheet AND playing music at the same time.
> A CPU just adds numbers.
No, CPUs can do a lot more than that. They perform comparisons, make decisions, service interrupts, read and write data to memory and to various IO devices, and more.
> Subtraction involves the addition of negative integers. Multiplication involves addition a number of times, and division involves subtraction a number of times.
Not directly, in most processors. There are probably some processors where you have to explicitly take two's complement and add, but most processors have a subtract instruction, and many can multiply and divide directly, too. Multiplication probably involves shifting and addition, not just addition.
> I think you are thinking of what is called parallel processors or parallel computing,
Not sure who you're referring to here. A single CPU can multitask, although to perform two tasks simultaneously (without cheating and "time slicing" to make it look like it's doing that, which is what single CPU multitasking OS's do) you must have multiple CPUs. This is what made the Amiga so powerful - it had separate chips for graphics, sound and so on, true multitasking and parallel computing.
> or cloud computing.
Heh, I don't think *anyone* knows what cloud computing really is yet. Seems to be a rehash of client/server architecture, where you have dumb clients and the real work is done on the server, or "cloud", where the cloud is now just a bunch of someone else's computers on the internet. Seems like a terrible idea to me; I want all my data locally where I can control it and where I'm not stuffed just because my internet connection has gone down.