The difficulty of the puzzle varies according to the number of filled cells at the beginning of each game. Write down every possibility for each cell.

If when you cross the rows and columns you find a blank space with only one possibility, you have found a naked single and the right answer for that cell.

Hidden singles are in fact naked singles that occur once you add a new digit to a row or a column. Keep your pencil notes updated and check them often through the game to find these.

These occur when you have two identical pairs of candidates in a single row or column. Even if you do not know their right placement, you can identify without a doubt their position in the grid.

Thus, you can eliminate those digits from any other possibilities in that row or column. Hidden pairs are cells with two identical candidates positioned in opposite corners of one square and nowhere else in the region.

This means that you can be certain that those two blank spaces can only be filled with one or the other.

They are called hidden pairs because there might be other candidates for the same cells which can make them hard to spot. Naked triples occur in rows or columns when you have three candidates that overlap.

The digits do not need to be the same for every cell, but this will tell you that those will be for certain in that row or column, allowing you to eliminate other possibilities.

You can then eliminate these numbers from your pencil notes on the remaining rows of their square. The grid in Sudoku is always changing.

Every time you place a digit, a number of possibilities open on other blank spaces. Check the ones immediately affected by the filled cell and you might find their answer right away.

Pay attention to the neighboring squares also, as their structure is very likely to have changed too. Sudoku is a simple game of logic.

Guessing should be your very last resort as it can easily throw off the puzzle and make it unsolvable. Review and update your pencil notes often to avoid cluttering the grid with possibilities.

The more candidates you note down, the noisier the puzzle will become which not only will it make it more stressful, but it can prevent you from finding easy numbers like naked singles.

Billions of free Sudoku puzzles are offered here online. The chance that you play the same Sudoku puzzle is almost zero. Play our billions of Sudoku puzzles on your mobile devices such as tablets and smartphones.

If you have a large screen phone, try both versions to see which one is a better fit for your device. We also encourage those mouse-only PC players to try our Sudoku Mobile page that has a "Cell First" option for entering multiple pencil marks in one cell at a time.

Our new smart solver not only gives the solution for a puzzle, but also explains every step with demonstrations in the grid.

Just click it again to return to puzzle number form. No payouts will be awarded, there are no "winnings", as all games represented by Games LLC are free to play.

Play strictly for fun. Also Try Sudoku Levels Sudoku Easy. Sudoku Medium. Sudoku Hard. Sudoku Expert. Use logic to solve this fun sudoku puzzle!

About Sudoku The popular Japanese puzzle game Sudoku is based on the logical placement of numbers. Sudoku Tips Sudoku is a fun puzzle game once you get the hang of it.

Work through the remaining empty cells, trying the numbers that have not been used. Tip 2: Break the grid up visually into 3 columns and 3 rows. Now, look for columns or grids that have 2 of the same number.

Logically, there must be a 3rd copy of the same number in the only remaining 9-cell section. Look at each of the remaining 9 positions and see if you can find the location of the missing number.

Now that you know a little more about Sudoku, play and enjoy this free online game. About Easybrain Easybrain is a mobile games publisher with the most popular Sudoku app on the App Store and Google Play, and from August is the proud owner of www.

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