Donut Sudoku: The Delectable New Variant

How sweet it is! Solvers will gobble up this delectable new sudoku variant with a tasty twist. No numbers appear within the central box to start, leaving a "donut hole" in the middle with the numbers that are given sprinkled around the edges. That makes breaking into the central area more challenging—and provides sudoku lovers with a unique solving experience.

Dr. Frank Rubin is a retired IBM® computer programmer who has done extensive work in the field of design automation, using computers to design the next generation of larger and faster computers. Dr. Rubin is also a cryptographer who holds major patents in the field of keyless cryptography. Beyond his professional activities, he has constructed thousands of mathematical puzzles, as well as cryptograms, alphametics, SumSum, Double Sudoku, and papers on knight and bishop coverings in chess. This is his first book for Puzzlewright Press.