When going through the Tour of Go programming language tutorial, the seventh lesson (https://tour.golang.org/basics/7) features an example of a "split" function. It accepts an integer, and multiplies by 4/9. Then it subtracts the result from the original number, resulting in two numbers that are the "split" of the original number (not necessarily in half).
It appears to me to be an arbitrary choice - any fraction works, because there's nothing special about the nature of splitting (not by half), and integer rounding of resulting float values is why it's always an integer (not because *4/9 always results in an integer).
But I wondered if there was some mathematical reference I was missing. 42 is frequently used in those examples and that's a sci-fi reference.