+ wishlist Sudoku for Brain Fitness: 90-Day Challenge to Sharpen the Mind and Strengthen Cognitive Skills (Brain Fitness Puzzle Games) [9780593689813] Add to Cart The item has been added Author: Steven Clontz Julie Demyanovich Sudoku for Brain Fitness: 90-Day Challenge to Sharpen the Mind and Strengthen Cognitive Skills (Brain Fitness Puzzle Games) [9780593689813] Buy More - Save More. Below are the available bulk discount rates for each individual item when you purchase a certain amount Quantity Price Savings 25 - 99 30% 100 - 249 32% 250 - 499 34% 500 - 999 36% 1000+ 38% List Price As Low as $12.99 Format: Paperback