→ dolphin100:我以為是小數點第二位 orz 08/18 15:30
※ 引述《dolphin100 (得分100~~YA)》之銘言：
: A total of 100 customers purchased books at a certain bookstore last week.
: If these customers purchased a total of 200 books, how many of the customers
: purchased only 1 book each?
: (1) None of the customers purchased more than 3 books.
: (2) 20 of the customers purchased only 2 books each.
: 答案是C ，可是我覺得很怪，搞不懂
In the decimal representation of x, where 0 < x < 1, is the tenths digit of x
nonzero?
(1) 16x is an integer.
(2) 8x is an integer.
答案是B ， 我也有大大的疑問
剛剛忘記看到這一題 = ="
ans:
1)一個小數*16會是整數 舉個例子 0.0625 or 0.125都可以
所以不知道小數第一位是否非0 不充分
2)*8會是整數 ex:0.5 0.25 0.125(最小)
所以小數第一位一定>0 答案B
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