In a nonconsecutive sudoku, adjacent numbers (horizontally or vertically) cannot be consecutive.
Let’s take a look at an example:
Let’s look at B5 (the middle box), and consider where the number 5 might be:
- R4 and C4 (shaded pink) already have 5s.
- Neither of the cells below and to the right of the number 6 in the middle (shaded blue) can have 5, according to the rule of nonconsecutiveness.
- Only one possibility is left in B5: R6C6.
The same method can be used to place the number 4 in B2 (the top middle box).
Download this puzzle as a PDF, print it and try to solve it yourself!