Classic Sudoku

THE PLAYBOOK · QTHCC

How to play Classic Sudoku

A round of Classic Sudoku at QTHCC begins with understanding the objective. Fill all cells with 1–9; do not repeat a symbol in any row, column or region. The learning focus here is mistake-aware practice, supported by the rule notes below.

Mistake-aware practice

Read the common mistake below before starting. Watch for that situation during the round rather than relying on trial and error.

Your goal

Fill all cells with 1–9; do not repeat a symbol in any row, column or region.

Step by step

1. Select an empty cell. The original clues cannot be edited.
2. Choose a symbol from the number pad, or type it on a keyboard.
3. Turn Notes on to record candidate symbols without committing an answer.
4. Use Check entries to check your filled values. Hint reveals one value from the verified solution.
5. Complete the board, or choose New puzzle for another board.

Controls

Tap or click a cell and use the number pad. Keyboard: arrows select cells; digits (and A–G on 16×16) enter values; Backspace erases.

A useful example

Before filling a cell, compare the symbols already used in its row, column and 3 × 3 region. A candidate must be absent from all three.

Watch out for this

Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule.

Common questions