Place every number 1–16 into the 4×4 grid, one per cell. Every clue is necessary; remove any one of them and the puzzle stops being solvable.
Clue count –
The Grid
Case Notes (Clues)
Definitions
Clear the grid?
This will erase every number and pencil mark you've entered and start the grid over from scratch. The clues, givens, and solution stay the same — only your progress is cleared. (You can still use Undo afterward if you change your mind.)
Reveal the solution?
This will fill in the full solution, replacing every number and pencil mark currently on the grid. (You can still use Undo afterward if you change your mind.)