Sudoku is a number placement puzzle, the aim of which is to enter a number from 1 through 9 in each cell of a grid, most frequently a 9x9 grid made up of 3x3 subgrids (called "regions"), starting with randomly placed numbers given in some cells (the "givens"). Each row, column and region must contain only one instance of each number. Its classic grid layout is reminiscent of other newspaper puzzles like crosswords and chess problems. The Little Book of Bathroom Sudoku offers 160 all-new puzzles for the sudoku addict and newcomer alike, in a range of difficulty levels.