Think of a number. Mathematical guesser

This book by the famous writer and popularizer of science Yakov Isidorovich Perelman "Think of a number" is not just one of many books on the shelves of bookstores: it is MAGICAL! Yes, yes! But if you don't believe it, carefully perform all the calculations mentioned here on the number you thought of - and the little book will guess the result of your calculations. If the result is different, check your calculations and make sure that you were the one who made a mistake, not the book. And in conclusion, the author will reveal the secrets of magic to you.