Puzzle · Logic

Sudoku

Fill the grid so every row, every column and every 3×3 box contains the numbers 1 to 9 exactly once. Every puzzle is freshly generated and has exactly one solution.

Sudoku tips for beginners

  1. Scan for singles. Pick a number, say 5, and look at each 3×3 box. If only one square in a box can hold a 5, it must go there.
  2. Look at the crowded rows first. A row with seven numbers filled has only two left, and the column or box usually tells you which goes where.
  3. Count what's missing. For a single square, list the numbers already in its row, column and box. If only one number is left over, that's the answer.
  4. Never guess. Every puzzle here has exactly one solution, so it can always be solved by logic alone.

Sudoku became popular worldwide in the 2000s, but number-placement puzzles are much older. A few minutes a day is good practice for concentration and logical thinking.