X-Sums Sudoku
The rule: Each outside clue is the sum of the first X digits in from that side, where X is the first of them.
Play unlimited X-Sums puzzles free — every one generated with a unique solution, rated by the solving techniques it actually needs.
- Four difficulties, from gentle to expert
- Step-by-step hints that teach, not just tell
- Interactive lessons and a daily race
- Make and share your own puzzles