Question

中译英。。

两位数：19.28.。。。。91等9个
三位数：首先在百位选定一个数，在选定十位则个位就可以确定，如百位是1，十位是0则各位就是9
百位是1时：十位可以时0，1.。。。。。。。9，共10个数。
百位是2时：十位可以是0.1.。。。。。。。。8，共9个数
。。。。。
百位是9时，十位可以是0.1共两个数
因此共有9+10.。。。。+2 =63个

Answer 1

Digit: 19.28.. . . . 91 three-digit such as 9: First, select a few hundred, ten were selected bits can be determined, as hundreds of 1, with 0 Members ten is one hundred is 1 9: Ten When bits 0,1.. . . . . . . 9, a total of 10 numbers. One hundred is 2:00: Ten can be 0.1.. . . . . . . . 8, number 9. . . . . One hundred is 9, a total of ten two numbers can be so 0.1 9 +10.. . . . +2 = 63