c语言编程计算!~急！！！！！！！！！

1． 编程计算 S1=1+2+3+……+99+100， S2=1+2+3+……n
2． 计算n+(n-1)+(n-2)…….+3+2+1
3． 计算1*2*3*……*n
4． 用循环实现输出1-10分别乘以10所得的乘法表
5． 接受12个月的工资，计算全年收入

谢谢了！~刚学不太会c编程！~
全部用c的while循环写~谢谢了~~~~~~~~~~我还没学到for- -！所以只能用while!

#include <stdio.h>
main()
{
int i,n;
int sum,prod;
float salary,total;

sum = 0;
i=0;
//求和
while(i<100)
{
sum += i;
i++;
}
printf("The sum from 1 to 100 is: %d\n",sum);

//输入n求和
printf("Input n:");
scanf("%d",&n);

sum = 0;
i=0;
while(i<n)
{
sum += i;
i++;
}
printf("The sum from 1 to %d is: %d\n",n,sum);

//第2问
printf("Input n:");
scanf("%d",&n);
sum =0;
i=n;
while(i>=1)
{
sum += i;
i--;
}
printf("The sum from %d to 1 is: %d\n",n,sum);

//第3问
printf("Input n:");
scanf("%d",&n);

prod = 1;
while(i<=n)
{
prod *= i;
i++;
}
printf("The product from 1 to %d: %d\n",n,prod);