Sudoku Rules

Fill every row, column, and 3x3 box with the digits 1 through 9 — each exactly once.

1. Every row, column, and bold-bordered 3x3 box must contain each digit 1–9 exactly once.
2. Tap a cell, then enter a number with the on-screen pad or your keyboard (1–9; Backspace or 0 to erase).
3. On the learning levels (1–10) each digit has its own color, so repeats are easy to spot at a glance.
4. On levels 10–20, entering a number highlights the whole row and column it affects — so you can see how each move constrains the grid.
5. Turn on pencil marks to note candidates, and use the Hint button to reveal the next logical step and why it works.
6. Pick your board size and a difficulty from 1 to 100. Prefer Kakuro? It is a number-crossword where each run of cells must add up to its clue using distinct digits.

Kakuro Rules

Fill each run of white cells with digits 1–9 so the run adds up to its clue — and no digit repeats within a run.

1. Each clue sits in a shaded cell: the number above the diagonal is the sum for the run going right; the number below is the sum for the run going down.
2. Fill the white cells of a run with digits 1–9 so they add up exactly to that run’s clue.
3. A digit may not repeat within the same run — though the same digit can appear in different runs that cross it.
4. Tap a cell, then enter a number with the on-screen pad or your keyboard (1–9; Backspace or 0 to erase).
5. Use pencil marks to note which digits could fit a run, and the Hint button to reveal the next logical step and why it works.

Sudoku · Kakuro