19 August,2010 12:30 PM IST | | Agencies
A mathematics wizard at Helsinki University has developed a sudoku which is so tough that it requires those attempting it "to think ahead eight or nine steps at a time".
Arto Inkala slogged over it for three months and used a specialised computer software that ran through billions of calculations.
"This one is much more difficult. It will take a long time to solve. No one's managed it yet," The Sun quoted Inkala as saying.
In a sudoku, the objective is to fill in the grid so every column, row and group of nine squares contain the digits one to nine.
Inkala said: "Normal sudoku puzzle logic eliminates the possibilities for each box in two or three steps.
"But this one requires puzzlers to think ahead eight or nine steps at a time - making very long deductions to eliminate the possible candidates for each box."
He had developed a sudoku in 2006, but that one was cracked by experts within 24 hours.
But this time, Inkala feels it would take weeks to solve.
And he added in good measure: "I'm already working on my next one."
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