I worked for a company where some people had done some computations (for plants and lines) in their heads or with notebooks or whatever for decades. Noone else knew how to do what they did, so the company decided to write a program to do it to ensure the future.
These guys told the programmers what they did, and then did not like the program. Indeed, they often decided what they wanted to see, and then put the numbers into the program to get the result they wanted, even though the numbers they put in were bogus and were only there to contrive the results they wanted to see.
So, the answer to favorite method of computation is simply, what i'm used to.