The problem: You have a list of numbers, some of which sum up to another number. If you have 10 numbers, there are 2^10 or 1,024 possible combinations. A pretty daunting task.
Recursion to the rescue. This file allows you to enter a list of numbers and a target, and it will tell you which numbers sum to the target.
Naishad Rajani wrote the code and Jimmy Day prettied up the UI. I only have the distinction of distributing the file. I did spend quite a bit of time stepping through this macro about five years ago. I had never used recursion at the time, and it was difficult to get my head around.
A word of warning. Twenty items in the list seems to be about the upper limit from a time perspective. Any more than that and it takes too long to process.