Fill the grid so every row and column holds each number from 1 to the grid size once. The numbers in each cage must make its target with its operation: add, subtract, multiply or divide (− and ÷ cages have two cells, in either order). Keys: arrows move, digits enter, Shift + digit or N for notes, Backspace erases, Z / Y undo and redo, H hint, C check, P pause.