A maths genius has created the world's toughest Sudoku.
Doctor Arto Inkala made the toughest puzzle after his previous Sudoku puzzle was cracked within hours.
"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.
"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," Inkala added.
He said that it would take weeks to solve the puzzle without help.
"I'm already working on my next one," he added.