<p>Arto Inkala slogged over it for three months and used a specialised computer software that ran through billions of calculations.<br /><br />"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.<br /><br />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.<br /><br />Inkala said: "Normal sudoku puzzle logic eliminates the possibilities for each box in two or three steps. <br /><br />"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." <br /><br />He had developed a sudoku in 2006, but that one was cracked by experts within 24 hours.<br />But this time, Inkala feels it would take weeks to solve.<br /><br />And he added in good measure: "I'm already working on my next one."</p>
<p>Arto Inkala slogged over it for three months and used a specialised computer software that ran through billions of calculations.<br /><br />"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.<br /><br />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.<br /><br />Inkala said: "Normal sudoku puzzle logic eliminates the possibilities for each box in two or three steps. <br /><br />"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." <br /><br />He had developed a sudoku in 2006, but that one was cracked by experts within 24 hours.<br />But this time, Inkala feels it would take weeks to solve.<br /><br />And he added in good measure: "I'm already working on my next one."</p>