Number puzzles: sudoku, killer sudoku and more

Puzzles built on numbers

Number puzzles are some of the most popular brain games in the world. Sudoku alone is searched millions of times every month. They are easy to learn, endlessly varied and perfect for a coffee break or a long evening.

Numbers play two different roles in these games. In Sudoku, Jigsaw Sudoku and Futoshiki they are just nine different symbols: you could replace them with colors or letters and the puzzle would be the same. What matters is logic, not arithmetic. In Calcudoku, Killer Sudoku and Mental Math the sums matter too, so they mix logic with a little quick counting.

Which number game to play

• Sudoku: the world’s favorite grid puzzle, from easy warm-ups to expert boards that need advanced techniques.
• Killer Sudoku: sudoku with cages that show a sum instead of given digits. Great once regular sudoku feels easy.
• Jigsaw Sudoku: irregular regions instead of 3×3 boxes, which breaks the usual patterns and makes you look again.
• Calcudoku: cages with a target and an operation, such as 12× or 3−. A good mix of arithmetic and logic.
• Futoshiki: a Latin square with greater-than and less-than signs between cells.
• Binairo: fill a grid with 0s and 1s so that no three in a row match and every row is balanced.
• Mental Math: a 60-second sprint of sums to keep your arithmetic quick and accurate.
• 2048: slide and merge tiles to double your way to 2048. More strategy than math.

Tips for number puzzles

1. Use every constraint. In sudoku, look at rows, columns and boxes together. In cage puzzles, list the few combinations that can make a sum.
2. Start with the extremes. A cage of 3 in two cells can only be 1 and 2. A cage of 17 in two cells can only be 8 and 9.
3. Write notes. Pencil marks are not cheating. They are how strong solvers work.
4. Practice a little every day. Short daily sessions build speed faster than rare long ones.

Frequently asked questions