AMC 8 2007 Problem 18
AMC8 2007 年第 18 题
余数与同余★★★☆☆
The product of the two 99 -digit numbers 303,030,303,...,030,303 and 505,050,505,...,050,505 has thousands digit and units digit . What is the sum of and ?
两个 99 位数字 303,030,303,…,030,303 和 505,050,505,…,050,505 的乘积的千位数字为 A，个位数字是 B。那么 A 与 B 的和是多少？
- A.3
- B.5
- C.6
- D.8
- E.10
正确答案 · Correct Answer
D
解析 · Solution
Solution 1
We can first make a small example to find out and . So, 303×505=153015 The ones digit plus thousands digit is 5+3=8.
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