100 Double CalcuDokus    by Giulio Zambon
Price: $0.99 USD. 1900 words. Published on December 7, 2011. .
If you like difficult Sudokus, you will love Double CalcuDokus. If you want to have fun and train your brain at the same time, CalcuDoku is for you. In this book, you will find exclusively Double CalcuDokus. That is, two CalcuDoku squares that overlap and have to be solved as a single puzzle. This gives an additional twist to the traditional CalcuDokus that makes them even more fun.