Sudoku X - 120 Easy To Master Puzzles 10x10 - 7 - John Collins - Bog

Diagonal Sudoku also called Sudoku X.The puzzle is a 10x10 grid made up of 5x2 subgrids (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, region and diagonal contains the numbers 1 through 10 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.