TRAVEL SIZE CALCUDOKU Do you love Sudoku, but are looking for something just a little different? Calcudoku is similar to Sudoku, but with a twist! You still complete the same grid with no numbers repeated in a row or column, but this time the numbers need to add to a target sum. For example, 2 squares in the grid may need to add to 5, so you can use 2 and 3 or 1 and 4. This book has all 4x4 and 5x5 puzzles, so it's a little bit of an easier introduction. This book of 4x4 and 5x5 ADDITION Calcudoku puzzles fits easily in your pocket or purse, so you can solve puzzles while you’re on the go. Difficulty is just right: not too easy or or too hard - 6"x9" (15.24cm x 22.86cm) - 6 puzzles per page - 500 puzzles - Solutions in the back