AMC8 2004
AMC8 2004 · Q8
AMC8 2004 · Q8. It mainly tests Basic counting (rules of product/sum), Digit properties (sum of digits, divisibility tests).
Find the number of two-digit positive integers whose digits total 7.
找出两位正整数各位数字之和为 7 的个数。
(A)
6
6
(B)
7
7
(C)
8
8
(D)
9
9
(E)
10
10
Answer
Correct choice: (B)
正确答案：（B）
Solution
(B) There are 7 two-digit numbers whose digits sum to 7: 16, 61, 25, 52, 34, 43 and 70.
（B）有 7 个两位数，它们的各位数字之和为 7：16、61、25、52、34、43 和 70。
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