KenKen

KenKen is a logic-based arithmetic puzzle game, often described as "math Sudoku."

How to play

You fill an n × n grid (typically 4×4, 6×6, or 8×8) with digits 1 through n, following two rules:

1. No repeats in any row or column (like Sudoku).
2. Cages: The grid is divided into heavily outlined groups of cells called "cages." Each cage has a target number and an operation (+, −, ×, ÷). The digits in that cage must combine (using that operation) to produce the target.
3. A single-cell cage just shows a number with no operation—that cell equals that number.