Everything you ever wanted to know about multiplication, division, calculations of all kinds and many other nice amenities… that you couldn’t even imagine.

Mental calculation can be interpreted as a game and – believe me – it is a funnier game than you might think, based not so much on the repetitive and boring application of a procedure, but on the ability to tailor the best way to do it each time, a way able to lead us to the solution without too much effort. It follows that exercizing a little bit with mental calculation is in fact a very valid training for our brain, it helps us to think better.
The repercussions are therefore also positive in real life, not so much because at the checkout we will be faster than the calculator to do the sums, but because our ability to make decisions will be refined, even under stressful circumstances. Don’t get me wrong, you don’t need to become a champion, just a little practice and the rust will fall off the mental gears.

Dario De Toffoli

From the preface by Furio Honsell:

“If we wish, we can read in the “Big Book” all the details of the algorithms and their reasons, climbing to the top of unexpected peaks to admire the beauty that comes from exactly combining simplicity with depth, but we are not forced to do so. The “Big Book”, just like the mountains, can be enjoyed both by those who want to breathe the fresh air on a pleasant walk, as by those who want the thrill and vertigo of the mountaineering challenge.”

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