#include<stdio.h>
int n_fact(int n);
void main()
{
     int n,res;
     printf("ENTER A NUMBER:-");
     scanf("%d",&n);
     res=n_fact(n);
     printf("%d",res);
}
int n_fact(n)
{
     int result;
     if(n=0)
        result=1;
     else
        result=n*n_fact(n-1);
     return(result);
}

#include<stdio.h>
int n_fact(int n);
void main()
{
     int n,res=0;
     printf("ENTER A NUMBER:-");
     scanf("%d",&n);
     for(i=1;i<=n;i++)
     {
        res+=n_fact(n);
     }
     printf("%d",res);
}
int n_fact(n)
{
     int result;
     if(n=0)
        result=1;
     else
        result=n*n_fact(n-1);
     return(result);
}

#include<stdio.h>
#include<conio.h>
long factorial(int,long);
void main()
{
int i,m;
long sum=0,k=1;
clrscr();
printf("enter ur no. of terms :");
scanf("%d",&m);
i=1;
while(i<=m)
{
   k=factorial(i,k);
   sum+=k;
   i++;
}
printf("the sum is : %ld",sum); 
getch();
}
 int factorial(int i,long k)
 {
     return (i*k);
 }

hope this also correct...
thank u