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 9x9 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 9, so you can use 1 and 8, 2 and 7, 3 and 6, or 4 and 5. This book of 9x9 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 and not too hard - 6"x9" (15.24cm x 22.86cm) - 2 puzzles per page - 180 puzzles - Solutions in the back