How to play Math Sudoku
- Press Start. Tap a square, then tap a number on the pad below the grid.
- Use each number exactly once in every row and every column, like a small Sudoku.
- Each bold cage shows a target and an operation. Its numbers must make the target: add for +, multiply for ×, and for − and ÷ use the two numbers in either order.
- Turn on Notes to pencil in candidates. A wrong number flashes red and counts as a mistake; three mistakes end the round.
- Fill the whole grid to finish. No mistakes and no hints earns three stars.
About Math Sudoku
Math Sudoku is a math cage puzzle, a close cousin of Sudoku that adds arithmetic. The grid is a square of a given size, say five by five, and you fill it with the numbers 1 to 5 so that no number repeats in any row or any column. On top of that, the grid is divided by bold lines into cages. Each cage shows a small target and an operation in its corner: 9+ means its numbers add up to 9, 2− means the difference between its two numbers is 2, 12× means they multiply to 12, and 3÷ means one divides the other to make 3. Cages with a single square simply give you that number. The first levels are three by three with addition only, so you can learn the idea in a minute; subtraction, multiplication and division arrive chapter by chapter, and the grids grow to seven by seven. Every puzzle was checked by a solver to have exactly one answer, so careful reasoning always gets you there. Notes let you jot down the numbers a cage still allows, and three mistakes end the round.
Controls
| Input | What it does |
|---|---|
| Tap a square | Select it (its row, column and cage light up) |
| Tap a number or 1 to 7 | Write it, or toggle a note in Notes mode |
| Arrow keys | Move the selection |
| N, Backspace, U | Notes on or off, erase, undo |
| H or Hint | Write the right number in a square (costs a star) (3 per level) |
Tips and strategy
- Start with the pairs that have few answers. In a five by five grid, 2÷ can only be 1 and 2 or 2 and 4, and 9+ over two squares can only be 4 and 5.
- Big products are your friends. A two-square 20× in a five by five grid must be 4 and 5, so the cage is solved except for the order.
- Use the row rule inside cages. Two squares of a cage in the same row cannot share a number, which often rules out a doubled pair such as 2 and 2 for 4×.
- Add up a whole row. The numbers in each row of an n by n grid always add up to the same total, so a row covered by cages tells you what the leftover square must be.
- Write notes for every square of a tricky cage, then cross them out as rows and columns fill in. The last candidate standing is the answer.
- When subtraction gives a large difference, it is pinned: in a six by six grid, 5− can only be 1 and 6.
Questions and answers
What is a math cage puzzle?
A Latin square puzzle with arithmetic clues: every row and column holds each number once, and outlined cages must make a target number with a given operation. It combines the logic of Sudoku with simple arithmetic.
Does the order matter for subtraction and division?
No. A two-square cage marked 2− can hold 3 and 1 in either order, and 2÷ can hold 4 and 2 in either order. Subtraction and division cages always have exactly two squares.
Can a number repeat inside a cage?
Only if the squares are in different rows and columns. Inside a single row or column, the usual no-repeat rule still applies.
Is there always one answer?
Yes. Every puzzle was checked by a solver, so it has exactly one solution that can be reached without guessing.
How are stars awarded?
Solve with no mistakes and no hints for three stars. Each mistake or hint takes one away, and any solve earns at least one.
Do I need an account?
No. Math Sudoku runs in your browser on phones, tablets and computers, and your stars and unlocked desk themes are saved on your device.
