Why is the square root of 5 approximately equal to 2.2360679774? How to compute the height of a tree without climbing on it? How to assess the surface of your flat? How to compute the sum of all integers from 0 until the year of your birth in 3 operations, and less than 2 seconds? Why and how are the two main words of this book introducing in a very clear and visual way some of the main concepts and relevant techniques used in calculus. Conceived...