Computers benefit from different kinds of tricks. The key difference is that computers don't have any trouble adding/subtracting arbitrary 8/16/32/64 numbers,

Computers benefit from different kinds of tricks. The key difference is that computers don't have any trouble adding/subtracting arbitrary 8/16/32/64 numbers, but human performance gets much worse when there's more than 1 or 2 non-zero or carrying. So while humans like to find ways to round things off, computers care more about minimizing the number of additions and multiplications, but don't have much preference for the (small, constant) complexity of each operation. (Except multiplying/dividing by powers of 10 -- both humans and computers prefer that)