统计数字问题一本书的页码从自然数1 开始顺序编码直到自然数n。书的页码按照通常的习惯编排， 每个页码都不含多余的前导数字0。-Statistics on the issue of a book page from the natural number 1 until the beginning of coding sequence of natural number n. Page book in accordance with the usual habit of scheduling, ea