Corner Sudoku vs Calc Sudoku: Rules and Examples

Nerdle currently lists both games in its official game catalog. We opened their level-one boards and entered a deduction in each on September 5, 2026.

In Corner Sudoku, every row, column, and 3 × 3 box contains digits 1–9 without repeats. The four corner cells of each box also add to the target displayed above the puzzle.

Suppose the target is 22 and three corners contain 3, 9, and 6. Their sum is 18, so the remaining corner must be 4. This matches the deduction we entered on the checked board. The target is a property of that puzzle; do not assume it is always 22.

Now reverse the process. If normal Sudoku logic leaves a corner with candidates 2 or 4, compare each with the other corners. The shared total may remove one candidate even when the row and column cannot.

In Calc Sudoku, thick boundaries group cells into cages. Each clue gives an operation and target. Digits cannot repeat within a row or column. Unlike Corner Sudoku, this game does not add a standard 3 × 3 box constraint.

On the six-digit board we checked, a two-cell cage labeled −5 included a given 1. The other cell had to be 6 because 6 − 1 = 5. We entered 6 in that cell. For a separate example, a two-cell ×12 cage on a 1–6 grid has candidate pairs 2 and 6, or 3 and 4; row and column exclusions decide which remain possible.

Use the digit range displayed by the selected level. A combination that works in a nine-digit puzzle may be impossible in a six-digit one. Also avoid carrying the 3 × 3 box rule over from ordinary Sudoku.

In Corner Sudoku, scan boxes with three known corners, then check rows and columns that are nearly full. In Calc Sudoku, start with small cages or targets with few possible combinations. Write down candidates before committing when more than one arrangement fits.

Both checked boards offered pencil, pen, undo, and hint controls. Use a hint when it will help you explain the next deduction, then try to make a following move yourself. Prefer Corner Sudoku if you already know standard Sudoku; try Calc Sudoku if you enjoy using factors and arithmetic combinations.

For a short arithmetic warm-up first, try our Mathlete practice routine. Teachers can adapt the examples with our classroom guide.

These Sudoku games are separate from Classic Nerdle. Our Nerdle solver handles Classic’s hidden equations, not Sudoku grids. For the daily equation, see today’s Nerdle answer when you are ready for the solution.