My understanding is a valid sudoku should have 1 unique solution. But in this one I just finished, the circled numbers seem to be interchangeable. Am I missing something?
My understanding is a valid sudoku should have 1 unique solution. But in this one I just finished, the circled numbers seem to be interchangeable. Am I missing something?
looks like the 9 in the bottom box is a pre-filled number, so couldn’t be swapped