If you get realy basic, you end up with a half adder. ( way way way oversimplified, so don't shoot me )
Say you have a "register" ( that is where the CPU stores the binary #'s that it is going to do the "operation" on. ) assume you want to add 2 numbers together. Lets say 10 and 8. Lets further assume this is a simple 8 bit address for simplicity.
First the CPU will get the #'s in binary form. 10 = 0 1 0 1 0 0 0 0 and 8 = 0 0 0 1 0 0 0 0
Then the CPU will "add" the binary 1's and 0's together. ( forgive below, text is always hard to draw in, and I am only going to show the first 5 bits, as the rest do not matter. )
0 1 0 1 0
0 0 0 1 0 +
-------------
If the CPU shows 2 0's being added together, that equals a 0 in the sum ( totals ) line. If it sees a 0 and a 1, then that = 1. If it sees a 1 and a 1, then it will make that a 0, and add a 1 to the next line.
So the answer we get for the above is:
0 1 0 1 0
0 0 0 1 0+
-------------
0 1 0 0 1 = 18 ( 2 + 16 )
Does that kind of help? That operation would be called a "cycle" or such.
Since you seem to be asking this as a non-computer person, I will show you how the "bits" are counted so the above makes more sence. AKA how to turn a # into a binary #.
The 0's and 1's are in a horizontal row above. That means that the 0 ( or 1 ) farthest to the left, counts as the numeral 1. the next is a 2. after that a 4, then an 8, 16 yada yada. see below
0 0 0 0 0 0 0 0 0 <---- 8 bits. every 0 that turns into a 1 gets counted as it's decimal equivalent.
1 2 4 8 16 32 64 128 <------ Sorry, but the forum automaticly deletes extra spaces.
So if the first and last 0's in the above 8 bits are 1's then we would get 1+128=129. If they are all ones, you would get 255, but including "0" we get the magicial # of 256.
Does that help more?
( Yes I know this is a HUGE simplication of what a CPU does, but I was trying to get it to the most basic so we can help Bigdog. )]
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What is the smallest calculation that a computer can make and what is it called >>
That above is the smallist calculation. The smallest unit ( part ) in a CPU is the transistor, and they work exactly as was described above, but that is not a calculation. A calculation is what is in my post above. In that respect the smallest calculation would be called a "Cycle" if I am understanding you correctly. I think the rest of these guys have been in HT too long, and it is getting to them

I on the otherhand, am used to working with ( forgive the term ) idiots at Home Depot. Who have no clue that a 2 x 4 is not actually 2 inches by 4 inches. I have a little more experence breaking down the easy answers into "Super Easy" digestiable chucnks that that same idiot can understand.
And no, I do not think you are an idiot. The guy who had never heard of a "shovel" was an idiot. ( yes, he asked me what is used to dig a hole in his yard, and when I said " A Shovel" he looked at me like I was speaking another language

)