4-6

#include <stdio.h>
double fact(int n);
int main(void)
{
    int i;
    double sum;
    sum=0;
    for(i=1;i<=100;i++)
 sum=sum+fact(i);
 printf("1!+2!+...+100!=%e\n",sum);
return 0;
}
double fact(int n)
{
    int i;
    double result;
    result=1;n;
    for(i=1;i<=n;i++)
    result= result*i;
    return  result;
}