> A more reasonable question would be, how many partially completed sudoku grids are there which have a unique solution. We don't know the answer to that. The

> A more reasonable question would be, how many partially completed sudoku grids are there which have a unique solution. We don't know the answer to that. The number of minimal Sudoku puzzles is estimated (with 0.065% relative error) to be 3.1055e+37 (or 2.5477e+25 for non-isomorphic minimal puzzles). See Bethier https://arxiv.org/pdf/1111.4083.pdf https://arxiv.org/pdf/1111.4083.pdf