AMC 8 2004 Problem 8
AMC8 2004 年第 8 题
基本计数原理★★☆☆☆
Find the number of two-digit positive integers whose digits total 7 .
求各个位上数字之和为 7 的两位正整数的个数。
- A.6
- B.7
- C.8
- D.9
- E.10
正确答案 · Correct Answer
B
解析 · Solution
Solution 1
The numbers are 16, 25, 34, 43, 52, 61, 70 which gives us a total of 7.
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