List Processing with Custom List
While FileMaker's calculation engine is super powerful for managing all kinds of unique calculations, the one thing it lacks is a feature for running a repetitive function across a range of data. This is certainly possible within the Scripting engine with the use of the ever wonderful Loop script step.
However, as stated, there's no way to really process a range of data using just a function. Unless... you create your own or use one which has already been created.
As it happens, there is just such a function which has long been one of the most powerful custom functions of all possible FileMaker custom functions. It was created over a decade ago and is still, too this day, one of the most powerful custom functions you could ever learn to use. The function is called CustomList and it's a must-know function for any FileMaker developer.