How to solve a Sudoku: a step-by-step routine
A simple routine for solving any Sudoku: scan for singles, add pencil marks, then look for pairs. Never guess. Learn the order that works. Solving techniques · lesson 7 of 7.
The lesson in words
Strong solvers follow a routine:
1. Cross-hatch each digit, 1 to 9, through every box.
2. Look for hidden singles in rows and columns.
3. When that dries up, add pencil marks and look for naked singles.
4. Then pairs and pointing pairs, which clear notes and reveal new singles.
Singles, notes, pairs, never guess. That’s the Sudoku path complete!
Questions
You’re stuck. What should you do?
Recheck your notes and look again. A guess that turns out wrong is very hard to undo.
Which digits are usually easiest to place first?
A digit that’s already on the grid six or seven times leaves very few places, so cross-hatching finds them fast.