Fill the grid so no number repeats in a row or column and every cage reaches its target with +, −, × or ÷
Calcudoku is a math cage puzzle, the same kind of puzzle many people know as KenKen. Like sudoku, every row and column of the grid holds each number exactly once: 1 to 4 on a 4×4 grid, 1 to 5 on 5×5 and 1 to 6 on 6×6. The grid is also cut into cages with thick outlines, and each cage shows a target and an operation. Its numbers must add, multiply, subtract or divide to that target. Ours builds a new puzzle each time you press New and runs a solver on it first: if a second answer exists, the generator changes a cage's operation or splits the cage until only one answer is left.
Pick a level: easy is a 4×4 grid with cages of up to two squares, medium is 5×5 with cages up to three, hard is 6×6 with cages up to four.
Press New puzzle. The small label in the top-left square of each cage is its target and operation, for example 12× or 3−.
Tap a square, then a number on the pad. Clear removes it.
A cage with + must add up to its target, × must multiply to it. A − or ÷ cage always has two squares: the larger number minus, or divided by, the smaller gives the target.
A cage of one square shows just a number: write it straight in.
On a keyboard, move with the arrow keys, type a number, press Backspace to clear and Ctrl+Z to undo.
With Show clashes on, a number repeated in a row or column turns red, and so does a full cage that misses its target. Fill the grid correctly to finish.
Mental arithmetic tied to logic. Each cage asks which numbers in range can reach a target by one operation, which means factoring products, splitting sums and listing the pairs with a given difference or ratio. Those short lists are then cut down by the rule that a row or column never repeats a number. The puzzle exercises quick, exact multiplication and division facts, working memory for the candidates you have ruled out, and the habit of checking one deduction against another.
Start with one-square cages, then with cages that allow only one set of numbers, such as 3÷ on a 4×4 grid (1 and 3) or 30× in two squares on a 6×6 grid (5 and 6).
Factor the × targets. On a 5×5 grid a 3-square cage of 60× has to be 3, 4 and 5, because 60 needs a 3 and a 5 and only 4 is left for the rest.
Every row and column adds up to the same total: 10 on 4×4, 15 on 5×5 and 21 on 6×6. If the cages filling most of a row are known, the last square is the difference.
A − cage with target 1 on a 6×6 grid has five possible pairs, so leave it until the row or column narrows it down.
Numbers may repeat inside an L-shaped cage when the repeats are not in the same row or column. Do not rule that out too early.
Leave Show clashes on while you learn the operations; switch it off when you want only the finished grid to tell you.
Calcudoku is a number puzzle on a square grid. Each row and column contains every number from 1 to the grid size once, and the grid is split into cages. Each cage has a target and an operation (+, −, × or ÷), and the numbers in the cage must produce the target with that operation.
They follow the same rules. KenKen is a trademarked brand name for this kind of puzzle; calcudoku is a generic name for it, and this game is our own build that is not connected to that brand.
They always cover two squares. For −, the larger number minus the smaller equals the target. For ÷, the larger number divided by the smaller equals the target. The order of the squares does not matter.
Yes, as long as the two copies are not in the same row or the same column. Only rows and columns are required to have no repeats.
Yes. Before a puzzle appears, a solver looks for a second answer. If one exists, the generator gives a cage a different operation that rules it out, or splits a cage where the two answers differ, and checks again until only one answer is possible.
The grid size and the largest cage: easy is 4×4 with cages of up to two squares, medium is 5×5 with up to three, hard is 6×6 with up to four. Each level keeps its own best time.
It is free with no sign-up. Your best time per level, the number of puzzles you have solved and the Show clashes setting are saved in this browser only.