Perhaps even more powerful would be spreadsheets + Prolog. Since Prolog's main strength is finding answers for you, I imagine putting that on grid would have very interesting results.
That sounds like a more powerful variation of Excel's Goal Seek function. The latter however uses an iterative approximation approach. Given the non-exact nature of floating point, it would be interesting to see if numeric approximation can be combined with a Prolog-like resolution algorithm.
Yes indeed!
Successful (caveat that term appropriately ;) versions of this prolog+floats idea have used interval analysis in the past.
Anyway, yep you can do it, and it is fun!