I am a beginner trying to write a program for my intro C class. I am trying to write a program that calculates the combination of numbers given a specific output by the user. The number has to be between 1-10 to be valid. I am not allowed to use the built in library that calculates a combination. I am getting stuck at the part where i need to calculate (n-k)! I see that my problem is after my loops the numbers the user inputs for n and k are now zero. I am not sure if I should have written this a different way or how I should go about getting the original entered digits back so that I can take and use them in calculating (n-k)! Any help would be very much appreciated.

```
int main() /* Main declaration with arguments */
{
int n,
nFact = 1,
k,
kFact = 1,
n_k = ( n - k ),
nkFact = 1,
combination;
do {
printf("\nEnter the number of items in the list (n): ");
scanf("%d", &n);
if ( n < 1 || n > 10 ) /* is n between 1 - 10 */
printf("\n?Invalid input: Number must be between 1 and 10\n");
else
break;
} while ( n > 1 || n < 10 );
/* As long as n>=1 program will loop the following n*n-1 */
while (n>=1)
{
nFact = ( nFact * n );
n = ( n - 1 );
}
printf("n! = %d", nFact);
do {
printf("\nEnter the number of items to choose (k): ");
scanf("%d", &k);
if ( k < 1 || k > 10 ) /* is k between 1 - 10 */
printf("\n?Invalid input: Number must be between 1 and 10\n");
else
break;
} while ( k > 1 || n < 10 );
while (k>=1)
{
kFact = ( kFact * k );
k = ( k - 1 );
}
printf("k! = %d", kFact);
while (n_k>=1)
{
nkFact = ( nkFact * n_k );
n_k = ( n_k - 1 );
}
printf("\n(n-k)! = %d", nkFact);
printf("\n");
system("PAUSE");
return(0);
}
```