# World’s hardest Sudoku puzzle is a numerical nightmare

The perfect companion to a boring cross-country flight, Sudoku puzzles are now as ubiquitous as crosswords. If you love logic, you probably love a good Sudoku.

If you love sanity, however, you probably won't love Arto Inkala, the Finnish creator of what's being called the hardest Sudoku puzzle in the world.

It works just like any other Sudoku puzzle: fill the 9x9 grid with numbers so that each column, each row, and each of the nine smaller 3x3 squares contain all of the digits 1 through 9. But solving this particular brain-melter is significantly tougher than the cakewalk you'll find in an in-flight magazine.

[Related: Play Sudoku Daily at Yahoo! Games]

How much harder? Sudoku puzzles are rated on a 'star' scale, with 1-star being the easiest and 5-stars being the hardest. Inkala believes his creation would tip the scales with an unthinkable 11-star rating. Yep. It goes to 11.

Inkala, however, isn't sure if it's technically the hardest one ever.

"It is difficult to say if any one [puzzle] is the hardest or not, because I believe the hardest one is not yet discovered," he cryptically told The Telegraph. "I am not sure if it is impossible to make, but there are so many possibilities to formulate that [I think] the most difficult one has not yet been found."

What makes this one so tricky is the number of deductions one has to make given the limited information from the outset. Inkala believes at certain points you'll have to be thinking up to ten moves ahead, roughly nine moves more than we're usually happy with.

Enough with the words. Can you solve this beast?

(Credit: Arto Inkala)

Don't feel too bad if you can't -- it was sort of designed that way. Click here for the solution!

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