Each row and column must contain every number from 1 to N exactly once — just like Sudoku.
Bold outlines group cells into "cages". The number + symbol in the corner is your target. The cage's numbers must produce it using that operation.
Every puzzle has exactly one solution, reachable by deduction alone. No trial and error needed.
Tap any cell — a number picker pops up right next to it. Pick your number. Done.