Question

对任意正整数 $n$ ，定义 $\boxed{n}$ 为 $n$ 的所有正因数之和。例如， $\boxed{6} = 1 + 2 + 3 + 6 = 12.$ 求 $\boxed{\boxed{11}}$ 。

For any positive integer $n,$ define $\boxed{n}$ to be the sum of the positive factors of $n.$ For example, $\boxed{6} = 1 + 2 + 3 + 6 = 12.$ Find $\boxed{\boxed{11}}.$

$13$

$20$

$24$

$28$

$30$

答案：D

知识点：因数之和自定义运算

难度评级：1150

解答：

首先，由于 $11$ 是质数， $\boxed{11} = 1 + 11 = 12$ 接着求 $\boxed{12}$ 。 $12$ 的因数为 $1, 2, 3, 4, 6, 12.$ 相加得到 $\boxed{12} = 28$ 。

所以正确答案是 D。

First, we find that $\boxed{11} = 1 + 11 = 12$ since $11$ is prime. Then we need to find $\boxed{12}.$ The factors of $12$ are $1, 2, 3, 4, 6, 12.$ Adding these yields $\boxed{12} = 28.$

Thus, D is the correct answer.

2007 AMC 8 第 10 题

答案：D

难度评级：1150

解答：

其他年份的第 10 题