Ooooooh, math games, I love them!
It's really fun to try to get the lowest possible value, there's a lot of stats involved. If it had a gamemode wher you tried to reach an exact value, I would love to try it too.
Only thing to say: it would be great to have a log somewhere to know what were our previous rolls, and/or what additions were performed last turn.
But apart from that, it's a good idea and I really like it. Good submission! ^^