About Calcudoku
The number puzzle the newspapers call KenKen, struck into cast-iron proving-plates on the casting floor of the Iron-Founders' foundry: bronze tags, raised iron ridges, chalk notes, and molten iron that runs through a mould the moment its sum is true.
Fill an n×n plate with the numbers 1 to n so that every row and every column holds each number once. Iron ridges cut the plate into moulds, and each mould's tag is its target and sign: its numbers must add, multiply, differ or divide to it. A − or ÷ mould always has two cells, and a one-cell mould's number is cast into the plate for you.
All 240 plates are open from the first visit, across six works from the 4×4 Nail to the 9×9 Cannon. Every one is proved to have exactly one answer by an independent count, and to be solvable by named reasoning with no guess anywhere; inside each work they run from gentle to hard.
Each plate keeps a named fastest first solve and a public top ten. The plate cards and the live clock both print the record and who holds it.
How to play
- Tap a cell, then a number: every row and column holds 1 to n once.
- Each mould's numbers must make its target with its sign: add (+), multiply (×), differ (−) or divide (÷). A − or ÷ mould has two cells: the larger number minus, or divided by, the smaller.
- Switch to Notes to chalk candidates; a struck number wipes itself from the notes in its row and column.
Controls
| Tap / click | Select a cell |
|---|---|
| Number pad / 1–9 | Strike a number (again to take it out) |
| Notes / Shift+number | Write a chalk note |
| N / S | Notes mode, strike mode |
| Delete / 0 | Clear the cell |
| Z / Escape | Undo, or return to the plates |
All 240 plates are open, deterministic, proved to need no guess and independently counted to one answer. There is no hint and no answer check: the page ships no solver and no answers, only the rules you can see (a clash in a row or column, a full mould that misses). Named fastest times, kept attempts, notes, sound and reduced-motion preference persist in this browser.
