mpg-guess
Wrote this up as a little guiding tool for Final Fantasy 14's mini-cactpot minigame. Enter the numbers as you have chosen them (or want to) to match what you have ingame, and it will add up and display possible sums for a given row.
Now it isn't precisely a useful tool - the potential rewards are probably not worth the extra effort of min/maxing the results - but it was more of a practice exercise for me.