About

Sudoku is the world's most popular number puzzle. The goal is elegantly simple: fill a 9x9 grid so that every row, column, and 3x3 box contains each digit from 1 to 9 exactly once. No arithmetic is needed — it's pure logic. Every puzzle has exactly one solution, reachable through deduction alone.

What makes Sudoku endlessly engaging is the way difficulty scales. Easy puzzles require only the simplest "last remaining digit" logic. Medium puzzles introduce hidden pairs and naked triples. Expert-level puzzles demand chains of logic that can span the entire grid. The same ruleset produces puzzles ranging from a 5-minute warm-up to a 45-minute deep dive.

Online Sudoku is perfect for focused breaks. The interface handles the bookkeeping — marking candidates, checking for errors — while you do the thinking. There's no time wasted on setup or cleanup. Just the puzzle and your brain.

How to Play

• Click any empty cell in the 9x9 grid and type a number from 1 to 9.
• Each row must contain every number from 1 to 9 with no repeats.
• Each column must contain every number from 1 to 9 with no repeats.
• Each of the nine 3x3 boxes must contain every number from 1 to 9 with no repeats.
• Use pencil marks to note possible candidates in cells before committing.

Tips

• Scan rows and columns first to find cells where only one digit can fit.
• Look for "naked singles" — a cell where only one candidate is possible.
• When stuck, find where a digit can go in only one cell within a box.

History

The modern Sudoku was popularized by Japanese puzzle magazine Nikoli in 1986, though an earlier version called "Number Place" was published in the US by Dell Magazines in 1979. British puzzle setter Wayne Gould created a computer program to generate Sudoku puzzles and brought them to the Times of London in 2004, sparking a worldwide craze. Within a year, virtually every major newspaper worldwide ran a daily Sudoku column.