AMC 8 2013 Problem 6
AMC8 2013 年第 6 题
表达式与运算★★☆☆☆
The number in each box below is the product of the numbers in the two boxes that touch it in the row above. For example, . What is the missing number in the top row?
下图中每个方格中的数字等于上一层和它相接触的两个方格内的数字之积。例如，30=6ｘ5.
那么在顶层的方格中，空白方格里的数字是多少？
- A.2
- B.3
- C.4
- D.5
- E.6
正确答案 · Correct Answer
C
解析 · Solution
Solution 1
The product of the two numbers in the second row is 600 600, so the missing number in that row is 600 30 = 20 30 600 =20. The product of 5 5 with the missing number in the top row is 20 20, so the missing number in the top row is 20 5 = 4 5 20 =4. Answer: 𝐶 C .
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