(also known as "Number Place") is a placement puzzle. The puzzle is most frequently a grid made up of sub grids (called "regions"). Some cells already contain numbers, known as "givens". The goal is to fill in the empty cells, one number in each, so that each column, row, and region contains the numbers 1 through 9 exactly once. Each number in the solution therefore occurs only once in each of three "directions", hence the "single numbers" implied by the puzzle's name. sudoku books for adults - sudoku book - sudoku and word search puzzle books - sudoku and crosswords book - sudoku game - sudoku gifts - sudoku and crossword puzzle books