Factorial program in c using function

#include <stdio.h>
long factorial(int);
int main(){
   int number;
   long fact = 1;
   printf("Enter a number to calculate it's factorial\n");
   scanf("%d", &number);
   printf("%d! = %ld\n", number, factorial(number));
   return 0;
}
long factorial(int n){
   int c;
   long result = 1;
   for (c = 1; c <= n; c++)
      result = result * c;
   return result;
}