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Sudoku Frequently Asked Questions

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What are the Sudoku Rules?

There is only one rule: place numbers 1 through 9 on the Sudoku board without repeating a number in any row, column or box.

That's it. Only one rule and yet so many puzzles, and so many skill levels to challenge the novice to expert solver.

How Many Sudoku possibilities are there?

There are 6,670,903,752,021,072,936,960 unique solvable Sudoku games. No one would ever be able to do every one of them.

Is it OK to guess when placing numbers?

No! It is not at all a good idea to guess. If the wrong number were placed in a cell it would "mess up" the game and you would end up getting very confused. Always make sure a value you're ready to place is correct before placing it.

It seems very natural in Sudoku to only place numbers when you know that that number is correct and goes in a given cell. However there are times, especially with difficult puzzles, when you're not sure what to do next and you may be tempted to place a number to "just try it." There are techniques called "trial and error" and "what-if" where you "try" a number or numbers but that is a different situation.

Is Sudoku Japanese?

Sudoku started in the United States. It has a Japanese name, and was made popular in Japan because of Maki Kaji and Nikoli Publishing. See the history of sudoku for the interesting details.

What does Sudoku Mean in Japanese?

Sudoku is an abbreviation of the Japanese phrase Suji wa dokushin ni kagiru, which translates to 'the numbers occur only once.'

Is Sudoku a Game or a Puzzle?

Sudoku is a logic based puzzle. Solvers use logic and memory to solve the puzzles.

Does Sudoku Require a High IQ?

Well, yes and no. Sudoku only has one rule, and you can learn how to play it in a matter of a minute or two. Once you know the rule, you start solving easy puzzles. So it doesn't require you to be in the top 5% of the smartest people in the world.

However, there are also sudoku puzzles that challenge even the most skilled solvers, and may require a computer to solve.

There are lots of skill levels between these two extremes, which makes sudoku fun and challenging. If you get bored with a skill level, you look for harder puzzles.

Does Sudoku Require Math?

There is no math required to solve sudoku puzzles. Sudoku can require logic, and a good memory helps. But no math skills are needed to solve them.

Sudoku doesn't even require numbers. Any set of letters, numbers, even punctuation, or a combination of them all can be used to create sudoku puzzles. You just need nine unique items. Even nine pictures or nine colors would work as items to put in a sudoku puzzle.

Wordoku is a variation of sudoku that uses a combination of letters, numbers and punctuation marks to make puzzles. You can put words and/or phrases in puzzles with wordoku.

Try it out - create your own wordoku puzzles.

Is Sudoku an Educational Game?

Well, yes and no. It is a puzzle/game which challenges the solver. So it can be considered an educational game. Many people solve sudoku because they're addicted to the game. Others solve it because they feel a sense of accomplishment when they solve puzzles at their skill level.

Regardless of the reason, sudoku is fun and challenging, and it improves the brain's ability to reason logically. So solvers keep their brains sharp when they solve sudoku.

Who is Howard Garns?

Howard Garns is widely known as the inventor of sudoku. He is credited with creating the puzzle and giving Dell the rights to include it in their puzzle magazines. When first published, it was called Number Place.

See the history of sudoku for more info on Howard Garns.