Nice.
I encountered a couple of screens where there was no correct answer available; MN=2, and there were no 1s on the grid. I suspect my 6-year-old granddaughter would protest.
I encountered a couple of screens where there was no correct answer available; MN=2, and there were no 1s on the grid. I suspect my 6-year-old granddaughter would protest.
1. I think I only got one grid that was unsolveable.
2. That was my first grid.
3. I was only playing with addition.
4. I completed exactly one round.
Because the "unsolveable" grid was my very first, I may well have pressed on without investigating too much, because perhaps things would become clearer; and indeed, all subsequent grids were easy to solve.
So please don't treat my comment as a bug report! If you've taken trouble to avoid that outcome, then almost certainly the error is me.