Sudoku Puzzle

Sudoku is a logic-based number placement puzzle played on a 9x9 grid, which is further divided into nine 3x3 subgrids (often called "boxes" or "regions"). The grid starts partially filled with numbers, and the goal is to fill in the remaining empty cells so that every row, every column, and every 3x3 box contains the digits 1 through 9 exactly once, with no repeats. What makes it engaging is that it requires no math in the traditional sense, just logical deduction. Each puzzle has a single unique solution that can be reached through reasoning alone, without guessing, by analyzing which numbers are already excluded from a given row, column, or box. Sudoku puzzles range in difficulty from easy to extremely hard depending on how many cells are filled in at the start and how complex the deduction chains are. While the modern format was popularized in Japan in the 1980s (the name means "single number" in Japanese), its roots trace back to 18th-century Swiss mathematician Leonhard Euler's work on Latin squares. It became a worldwide phenomenon in the mid-2000s and remains popular in newspapers, puzzle books, and apps today.