Sure, I could calculate the best value for a resistor to get my buck converter to output 5V... or I could just write a script that tries all combinations of resistors I have on hand and outputs the ones that produce an in-tolerance voltage.

@ryanc Related: Years ago, I saw a video on how these packs of three mushrooms, are packed for a fixed net weight of 100g (or whatever). There was a worker with 8 (or so) scales in front of them. On each one, a mushroom would be placed.
Then three of the scales would light up, indicating the mushrooms that together add to the target weight. They would package these up and place three new mushrooms, and different lights would light up, etc.