Book excerpt: Balance Quest is a numeric progression puzzle consisting of a set of rectangles arranged within a hierarchical grid. Some of the rectangles contain positive or negative integers, while others are blank. The objective is to fill in each blank rectangle with an integer in a way that “balances” the puzzle mathematically. The puzzle features three skill levels (Easy, par, and challenging) with three grid sizes: BQ Sixteen (small-grid), BQ Thirty-two (medium-grid), and BQ Sixty-four (large-grid). Solve time can range from 5 minutes for the "easy" small puzzles to hours for the "challenging" large puzzles. This puzzle is for ages 10+.