#define _CRT_SECURE_NO_WARNINGS 1#include<stdio.h>
#include<math.h>
int main()
{int i,n;double s=0.0;printf("输入任意一个自然数： ");scanf("%d",&n);for(i=1;i<n;i++) {if(i%3==0&&i%7==0){s+=i;}}s=sqrt(s);printf("%lf\n",s);return 0;
} 
//函数名: sqrt
//功 能: 计算平方根
//用 法: double sqrt(double x);
//需要添加 #include <stdio.h> 头文件#include <math.h>
#include <stdio.h> int main(void) { double x = 4.0, result; result = sqrt(x); printf("The square root of %lf is %lf\n", x, result); return 0;
} 
 - 验证)
