英语翻译In how many of the integers between 1 and 100 does the digit 5 occur exactly once (A) 10 (B) 18 (C)19 (D) 20 (E) 21求翻译以及解题思路

英语翻译
In how many of the integers between 1 and 100 does the digit 5 occur exactly once
(A) 10 (B) 18 (C)19 (D) 20 (E) 21
求翻译以及解题思路

从1到100的整数里有多少个数里,恰好有一个数字5?答案B.
5,15,25,35,45,65,75,85,95,50,51,52,53,54,56,57,58,59.