How many integers between 324,700 and 458,600
have tens digit 1 and units digit 3?
(A) 10,300
(B) 10,030
(C) 1,353
(D) 1,352
(E) 1,339
答案是E,我不明白tens digit 1 and units digit 3是什么意思,是说十位数十1,个位数十3吗?应该选A啊?
If the sum of the first n positive integers is S , what is the sum of the first n positive even integers, in terms of S ? 我的理解是n个整数和为S,偶数和应是s/2啊,但是答案是2S,
我的理解错了吗
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