KenKen

KenKen is a logic-and-arithmetic puzzle invented by Japanese maths teacher Tetsuya Miyamoto in 2004. Solvers fill an N×N grid so each row and each column contains 1 through N with no repeats. The grid is divided into 'cages' (small groups of cells) each with a target number and arithmetic operation — cells within a cage must combine to the target using that operation. Published globally including by the New York Times.