ncr means : combination in terms of mathematics.We have to find out the perfect combination of given values. In the mathematics nCr has defined as nCr = n! /((n-r)! * r!)

    #include
    int main(){
      int n,r,ncr;
      printf("Enter any two numbers->");
      scanf("%d %d",&n,&r);
      ncr=fact(n)/(fact(r)*fact(n-r));                              //fact denotes factorial of a number .
      printf("The NCR factor of %d and %d is %d",n,r,ncr);
      return 0;
    }
     int fact(int n)                                                    // this is a factorial finding function
    { 
      int i=1;
      while(n!=0){
          i=i*n;
          n--;
      }
      return i;
     }

  sample output:
    6 4
    The NCR factor of 6 and 4 is 15