We’ll school you in sudoku! Find your grade, improve your play—and graduate to the next level. Sudoku professor Frank Longo has crafted five books with 300 sudoku each, which will take students from solving basics to super-hard, super-expert strategies. Try them and see how far you can go! Things are getting tough here! Now solvers can put their skills to the test with 300 medium-hard to hard puzzles. By the end of the book you’ll be working on upper-level techniques.