By the RatzBrain Editorial Team | 10 Minute Read
Moving from easy to hard Sudoku puzzles is a significant milestone for any enthusiast. While basic puzzles can often be solved by simply looking for missing numbers, harder grids require a structured approach to logical deduction. In this guide, we explore the mental framework necessary to tackle Expert-tier puzzles.
Expert Sudoku isn't about guessing; it's about identifying what cannot be in a certain cell. We recommend using 'pencil marking'—specifically the Snyder Notation—where you only mark candidates when they can only appear in two cells within a 3x3 block. This keeps the grid clean and makes patterns like 'Hidden Pairs' jump off the screen.
Begin by scanning each row, column, and block for 'Naked Singles'—cells where only one number is mathematically possible. Once these are exhausted, look for 'Hidden Singles'—numbers that can only fit in one specific cell within a block, even if that cell has multiple candidates listed.