Play Calcudoku — Free
The arithmetic Latin-square puzzle. Fill every row and column with 1–6 — no repeats — while the numbers inside each outlined cage combine with +, −, × or ÷ to hit its target. Hand-crafted Easy, Medium and Hard boards, each with one guaranteed solution.
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What is Calcudoku?
Calcudoku is an arithmetic logic puzzle that fuses the tidy discipline of a Latin square with a sprinkle of easy mental math. On the vygam version you are handed a six-by-six grid, and your first job is the one every Sudoku fan already knows by heart: fill it so that every row and every column contains the numbers 1 to 6 exactly once, with no repeats in any line. That alone would make it a Latin square. What turns it into Calcudoku is the way the grid is carved into bold-outlined groups of cells called "cages". Each cage carries a small target number and a math operation, and the numbers you write inside a cage must combine — by adding, subtracting, multiplying or dividing — to produce that target. It is the trademark-free version of the famous arithmetic cage puzzle, so you get exactly the same brain-teasing gameplay under an open, generic name.
Because it welds two kinds of logic together, Calcudoku feels both instantly familiar and pleasingly different. The Latin-square half is pure elimination — the same cross-hatching instinct that cracks a Sudoku — while the cage half asks you to reason about which small numbers can possibly combine to hit a target. A cage marked "11+" spanning two cells, for instance, can only be a 5 and a 6, which is often the thread that unravels a whole corner of the board. The arithmetic never gets harder than a primary-school sum, so nobody needs to be a "maths person" to enjoy it; the challenge lives entirely in the deduction. Every puzzle on vygam is hand-crafted with a single guaranteed solution reachable by logic alone, so you can always work your way to the answer one forced number at a time — never by guessing — and a whole 6×6 board fits neatly into a coffee break.
How to Play Calcudoku
The four operations tell you how a cage's numbers fit together. For + (add) and × (multiply) a cage can be any size, and the order of the cells does not matter — every number in the cage simply adds, or multiplies, to the target. For − (subtract) and ÷ (divide) the cage always has exactly two cells: you take the larger of the two numbers with the smaller, so the difference (larger minus smaller) equals the target, or the larger divided by the smaller equals the target. A single-cell cage is just a given — it shows one number, which is simply the answer for that square.
A placement or a finished grid is wrong whenever it breaks one of these rules:
- a number from 1 to 6 appears more than once in the same row;
- a number from 1 to 6 appears more than once in the same column;
- a completed cage's numbers do not combine to its target — for example a "+" cage whose cells add up to the wrong total, or a "−" cage whose two numbers differ by the wrong amount.
Calcudoku Tips & Strategy
Calcudoku rewards a good order of attack. The trick is to let the cages and the Latin-square rule feed each other — every number a cage forces removes a candidate from its row and column, and every row or column you nearly complete narrows what a cage can hold. These techniques will get even the Hard boards moving.
Start with the most constrained cages
Hunt for cages whose target leaves almost no freedom. On a 1-to-6 grid a two-cell "11+" must be 5 and 6, a "10×" must be 2 and 5, and a two-cell "5−" can only be 1 and 6. Single-number cages are handed to you outright. Lock these in first, because each one plants a definite value that ripples out through its row and column and starts a chain of eliminations everywhere else.
List a cage's combinations, then prune
For a trickier cage, write down every set of numbers that could reach its target, then throw out the ones that break the no-repeats rule. A three-cell "8+" could be 1-2-5 or 1-3-4, but if that cage shares a row that already contains a 1, both of those still fit — whereas a cage sharing a column that holds a 4 kills the 1-3-4 option. Pencil-marking the surviving candidates in each cell turns a fuzzy cage into a short, checkable list.
Cross-hatch like Sudoku
Beneath the arithmetic, Calcudoku is still a Latin square, so classic scanning pays off. Pick a value, say 4, and check which rows and columns already contain it; a cell where its last legal row and last legal column intersect must be a 4. Combine this with the cage logic — often a value is forced into a region by cross-hatching, which in turn completes a neighbouring cage and unlocks the next deduction.
Use parity and multiples as shortcuts
The math itself leaks information. A "×" cage target that is odd cannot contain any even number, so a two-cell "15×" must be 3 and 5. A target that is a multiple of 5 almost always needs a 5 in the cage, and a large product like "120×" over three cells quickly narrows to a handful of factor sets. Reading a cage's target as a factoring or parity clue, rather than just a sum to check at the end, often reveals a number long before the surrounding cells would.
Difficulty Levels & Puzzles
vygam ships three tiers of hand-crafted Calcudoku, and every puzzle is authored with a single guaranteed solution reachable by logic alone. Easy boards give you a handful of single-cell givens and lean on small, friendly two-cell cages using addition and subtraction — the perfect place to get comfortable reading a target, spotting forced pairs and settling into the "1 to 6, once each" rhythm of a row. They solve quickly and rarely ask for more than a glance at a cage to see its answer.
Medium puzzles pull back most of the givens and mix in multiplication and division cages, so you rely more on listing combinations and cross-hatching. Hard puzzles hand you the fewest clues — sometimes none at all — and lean on bigger cages and large multiplication targets, so a single well-read "×" cage can carry more weight than any given number would. Your fastest completion is stored separately for each difficulty in your browser, so you can chase a personal-best time on Easy while slowly working up to the Hard set. Tap New puzzle at any time to move to the next board in the current tier — the collection cycles, so there is always another grid waiting.
Calcudoku vs Sudoku & Other Logic Puzzles
If you already enjoy Sudoku, Kakuro, Futoshiki or Nonogram, Calcudoku will feel like a close cousin with an arithmetic twist. Like Sudoku it is built on the Latin-square rule — fill each line with a set of symbols and never repeat one — but it swaps Sudoku's fixed 3×3 boxes for free-form cages that carry math targets, and it shrinks the grid to a brisk 6×6. That makes an individual Calcudoku much faster to finish, while the cages add a layer of number-combining logic that Sudoku never asks for. Where a Sudoku solver only counts what is missing from a box, a Calcudoku solver also weighs which sets of small numbers can possibly hit a target.
Compared with Kakuro, which hides its constraints inside crossword-style sums, Calcudoku is more varied: it uses all four operations rather than addition alone, and its cages sit right on the grid for you to read at a glance. Against Futoshiki, which layers greater-than and less-than signs onto a Latin square, Calcudoku trades ordering clues for arithmetic ones — you compare products and sums instead of chasing chains of inequalities. And against a picture-forming puzzle like Nonogram, Calcudoku is purer deduction: there is always a next logical step and never a moment where you must gamble. That blend of a small, quick grid and completely transparent rules is exactly why Calcudoku has become a favourite warm-up for puzzle fans, and why it plays so well as a short, thinking break in your browser.
FAQ
Is Calcudoku free to play?
Yes — Calcudoku on vygam is completely free and plays instantly in your browser. There is no download and no sign-up; you can play Easy, Medium and Hard puzzles on phone, tablet or desktop whenever you like.
How do you play Calcudoku?
Fill the 6x6 grid so every row and every column contains the numbers 1 to 6 exactly once, exactly like a Latin square. The grid is split into bold-outlined groups called cages, and each cage shows a target number with a math operation. The numbers you write inside a cage must combine using that operation to make the target. When the whole grid is a valid Latin square and every cage hits its target, the puzzle is solved.
What do the +, −, × and ÷ cages mean in Calcudoku?
The symbol next to a cage's target tells you how its numbers combine. A plus cage means the numbers add up to the target and a times cage means they multiply to it — for these the order of the cells does not matter. A minus or divide cage always has exactly two cells, and you take the larger number combined with the smaller: for minus the difference equals the target, and for divide the larger divided by the smaller equals the target.
Do you need to be good at math for Calcudoku?
Not really. Calcudoku only uses the numbers 1 to 6 and simple whole-number arithmetic — small sums, differences, products and exact divisions. There is no algebra and nothing to calculate on paper. The real skill is logic: working out which arrangement of a cage's numbers fits both its target and the no-repeats rule of its rows and columns.
Is Calcudoku harder than Sudoku?
Calcudoku uses a 6x6 grid rather than Sudoku's 9x9, but it layers arithmetic cages on top of the Latin-square rule, so each cage gives you two clues at once — the math target and the no-repeats constraint. Many players find Easy Calcudoku gentler than Sudoku, while Hard boards with big multiplication cages and few given numbers can be every bit as demanding as a tough Sudoku.