Learning how to solve Sudoku puzzles requires applying logic. There are over thirty Sudoku techniques you need to know in order to solve all Sudoku puzzles from easy to fiendish. I cover some of these techniques on this website.
Solve Sudoku Puzzles Using The Scanning Technique
You don’t need to pencil in all the candidates. I only pencil in a candidate when it is limited to two cells in a row, column, or 3×3 region. Applying logic as you solve a puzzle will determine which cell will be solved by the candidate.
As you solve a cell, use that new number to see if you can solve additional cells in another 3×3 region.
Candidate Elimination Techniques
As you progress to harder puzzles you can use candidate elimination techniques. In this case,I would pencil in all the candidates once I reached a point where simpler techniques such as scanning, stop working.
If you don’t like to pencil in candidates you can enter your puzzle into a software program such as Simple Sudoku
All the candidates can be automatically “pencilled in” saving you tedious labor. Or you can enter your puzzle on my blank grid with candidates.
When you use this tool, all you need to do is use “white out” to remove candidates as you enter the “givens” and as you solve cells.
Learning how to solve puzzles using candidate elimination techniques will help you solve harder Sudoku puzzles.
In my article on Sudoku Tips, I cover many of the common candidate elimination techniques.
Advanced puzzles may need advanced techniques such as X-Wing, XY-Wing, Swordfish, locked candidates, linked pairs, coloring and more. Check my other pages for instructions on how to solve Sudoku puzzles using these techniques.