ABSTRACT
You know how to compute the average of a set of numbers https://www.w3.org/1998/Math/MathML"> x ¯ : = ( x 1 + x 2 + ⋯ + x n ) / n https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781032709659/c7a4d4a1-2867-4f77-92fe-2269316fcfe7/content/math5_91_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> or you wouldn’t even have picked up this book. In solving puzzles, it’s often useful to reverse this process, and compute the sum from the average instead.
