Start by scanning rows and columns horizontally and vertically. Look for cells with only one empty cell. Pencil in all possible numbers and erase them as you solve. Focus on sections with fewest empty cells first
Use pencil for harder puzzles to erase marks and track progress. Write down potential candidates in open boxes. Scan cells mentally to internalize given numbers
Contains optimal solutions for all F2L cases. Arranged in six different corner and edge combinations. Uses three different triggers for easier memorization
Evil level is the most difficult sudoku level with fewer clues. Puzzles have more complex patterns and symmetries. Solving requires high skill and experience
Sudoku evolved from Japanese number puzzle. British newspaper The Times started daily sudoku in 2004. Puzzles spread worldwide, appearing in major US and French newspapers. Japanese elementary schools began incorporating sudoku into math classes
Puzzles include solutions to 10 Sudoku puzzles. Solutions provided by KrazyDad.com. Puzzles feature quotes from famous philosophers and authors