Sudoku Challenges

The Sudoku challenge is a logical-based combinatorial number puzzle. The goal is to fill a 9 × 9 grid with digits so that each column, each row, and each of the nine 3 × 3 subgrids forms a grid (also called a "box" or "block") containing all the digits from 1 to 9. Each puzzle will start at a partially completed grid, which has a unique solution.