The Times Killer Su Doku 4

Specially compiled to provide the most devilishly difficult challenge, the Ultimate Killer Su Doku gift set is ideal for Su Doku enthusiasts who need a puzzle that really tests their mettle. With 360 puzzles. This pack includes: The Times Ultimate Killer Su Doku Books 4, 5 and 6. Prepare yourself for the toughest Su Doku challenge there is. These diabolically difficult Ultimate Killer Su Dokus will really put your brainpower to the test as you take on 300 Deadly Killer puzzles before steeling yourself to take on the 60 Extra Deadly Su Dokus. Are you ready for the challenge? These puzzles are not for the faint-hearted. Using the same 9x9 grid as a regular Su Doku, but have an extra mathematical element that makes them a real challenge. The aim is not only to complete every row, column and cube so that it contains the digits 1 to 9, but also to make sure that the outlined sections, called cages, add up to the number given in each cage. Warning: Not suitable for amateur puzzlers.