A number puzzle is a type of puzzle that involves manipulating numbers. Two popular examples of number puzzles are Sudoku and Soduko. Sudoku is a logic-based, number-placement puzzle where the objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 subgrids that compose the grid contain all of the digits from 1 to 9. Soduko is similar to Sudoku, but instead of a 9x9 grid, it uses a 6x6 grid. The objective is to fill the grid with digits so that each column, each row, and each of the four 2x3 subgrids that compose the grid contain all of the digits from 1 to 6.