Just when you thought it was safe to pick up a pencil Killer Su Doku is based on the original Su Doku grid, with the same rules and numbers—1 to 9—but with

The latest volume in the Killer Su Doku series from the puzzle suppliers to The Times features the highest-quality puzzles with an extra element of arithmetic.

Killer Su Doku poses an even greater challenge than the Fiendish Su Doku puzzles.Here are 100 previously unpublished puzzles for hard-core Su Doku addicts.

Challenge your brain with these enjoyable puzzles. Specially compiled to provide the most deadly Su Doku challenge, this is the only volume for Su Doku enthusia