About Sudoku

Sudoku is a logic puzzle — not a maths test. The grid is 9×9, divided into nine 3×3 boxes. Your goal is to fill every row, column, and box with the digits 1 through 9, using each digit exactly once in each unit.

When you start a puzzle, some squares are already filled in. These are called the givens — the starting clues from which you work out the rest. They cannot be changed. The fewer givens a puzzle has, the harder it tends to be, but placement matters as much as quantity.

Your task is to fill in the empty squares without repeating any digit in the same row, column, or box. Think of the puzzle as something that was once complete and then partially erased: your job is to restore it, one logical deduction at a time.

The key insight is that every solved square creates new constraints. If the digit 7 already appears in a row and a column, it can only go in one specific cell in the 3×3 box they share. Work through those constraints systematically — every puzzle has exactly one solution, and no guessing is required.

Difficulty is set by how many givens the puzzle contains and how they are arranged. A beginner puzzle might start with 36–40 filled cells; an extreme puzzle may have fewer than 25. The logic is the same at every level — only the number of deductions between you and the solution changes.