4×4 Calcudoku
A 4 × 4 grid with addition and subtraction cages. Put 1 to 4 in every row and column so every cage hits its target.
How to play
- Fill the grid so every row and every column contains each number from 1 to 4 exactly once.
- The thick lines split the grid into cages. The small clue in the corner of each cage gives a target and an operation: the numbers in that cage must make the target using that operation.
- For − and ÷, start from the bigger number: a “2÷” cage could hold 3 and 6, in either order. A cage with no operation is just that number.
- Tap or click a square, then tap a number or type it. Turn on Notes to pencil in possibilities. Repeated numbers turn red, and so does a cage clue when its full cage misses the target.
What it practises
- Addition and subtraction facts to 10
- Finding number pairs with a given difference
- Logical reasoning
Level: Ages 7–10 (Grades 2–4)
Tips for 4×4 Calcudoku
A “3−” cage with the numbers 1 to 4 can only be 1 and 4. Look for clues like this that have just one answer.
Each row adds up to 1 + 2 + 3 + 4 = 10. If a row is covered by cages you know, you can work out the missing square.
Questions and answers
How does subtraction work in Calcudoku?
A subtraction cage has two squares. Take the smaller number from the bigger one to get the target, whichever way round they are in the grid. So “1−” could be 3 and 4, or 2 and 1.
Does every puzzle have exactly one solution?
Yes. Every puzzle is checked when it’s made, so there’s only one correct way to fill the grid and it can be found without guessing.
What comes after 4×4 Calcudoku?
Try 5 × 5 Calcudoku, which adds multiplication and division cages.