Bài 11: Tính S(n) = 1 + 1.2 + 1.2.3 + + 1.2.3 N
#include<stdio.h>
#include<conio.h>
int main()
{
int i, n;
long S, P;
S = 0;
P = 1;
i = 1;
do
{
printf("\nNhap n: ");
scanf("%d", &n);
if(n < 1)
{
printf("\nN phai lon hon hoac bang 1 Xin nhap lai !"); }
}while(n < 1);
while(i <= n)
{
P = P * i;
S = S + P;
i++;
}
printf("\nTong la %d",S);
getch();
return 0;
}