Kakuro (Cross Sums) uses a crossword grid with number sums instead of words. Digits 1–9, no repeats per block. Second only to Sudoku in Japan. Pure logic—arithmetic-free despite the sums.
ルール
Grid like a crossword; clue cells show a sum and arrow for a block. Fill white cells with 1–9 so block digits sum to the clue; no repeat in a block. Use forced combinations: 3 in 2 cells = 1+2; 16 in 2 = 7+9; 45 in 9 = 1–9. Crossing blocks eliminate candidates. Solve by logic; unique.
歴史
Cross Sums in US 1950; Nikoli popularised in Japan. "Kakuro" pun on kuro (black) and kazu (number). Second pillar of Japanese puzzle culture after Sudoku. Dell puzzle magazine staple in the West.
戦略のヒント
Memorise key forced combinations: 3 in 2 = 1+2; 4 in 2 = 1+3; 16 in 2 = 7+9; 17 in 2 = 8+9; 45 in 9 = 1–9. Use crossing constraints—every cell belongs to a horizontal and vertical block.
文化的背景
Japanese puzzle culture's second pillar; Dell magazine staple; strong app ecosystem. Arithmetic reputation puts off some but it is pure logic. Kakuro (Cross Sums) uses a crossword grid with number sums; digits 1–9, no repeats per block. Forced combinations (3 in 2 = 1+2, 16 in 2 = 7+9) drive the logic. Available on Nikoli.com, Conceptis Kakuro, and Simon Tatham's Portable Puzzle Collection. Second only to Sudoku in Japanese puzzle culture.
購入・プレイ
- Kakuro Puzzle Book (Nikoli) Official Nikoli kakuro collection
- Kakuro Mega Puzzle Book (200+ puzzles) Large-format Western kakuro puzzle book
- Play Kakuro free online (KrazyDad) Free printable and browser kakuro puzzles by difficulty