Menghitung Deret Aritmatika

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    int a, b, n, hasil, jumlah;
    cout<<"Masukkan Suku Pertama : ";
    cin>>a;
    cout<<"Masukkan Beda : ";
    cin>>b;
    cout<<"Masukkan Banyak Suku : ";
    cin>>n;
    hasil = a +(b*(n-1));
    jumlah = (a + hasil )* 1/2*n;
    cout<<"Suku ke %i = "<<hasil;
    cout<<"jumlah suku pertama = "<<jumlah;
    system("PAUSE");
    return 0;
}

Menghitung Deret Fibonacci

#include <cstdlib>
#include <iostream>
#include <conio.h>

using namespace std;
class Operator{
      friend ostream& operator <<(ostream&, Operator&);
      friend istream& operator >>(istream&, Operator&);
public:
       long fibonacci(int);
private:
        int n;
};

int fibonacci(int n){
    if (( n == 1 ) || (n == 2)) return (1);
    else return (fibonacci(n-1)+ fibonacci(n-2));
}

ostream& operator <<(ostream& out, Operator& a){
         for (int i=1; i<=a.n;i++)
         out<<fibonacci(i)<<" ";
         return out;
         }
        
istream& operator >> (istream& in, Operator& a){
         cout<<"Sampai suku ke : ";
         in>>a.n;
         return in;
         }

int main(int argc, char *argv[])
{
    Operator run;
    cin>>run;
    cout<<run;
    system("PAUSE");
    return EXIT_SUCCESS;
}

Menghitung Deret Geometri

#include <cstdlib>
#include <iostream>

using namespace std;

class geometri{
      public:
             geometri();
             void masuk();
             void proses();
             void keluar();
            
      private:
              int a,n,r;
              float bil[100];
              float total;
      };

geometri::geometri(){
                     cout<<"Menghitung Deret Geometri\n\n";
                     }
                    
void geometri::masuk(){
     cout<<"Nilai a      : ";
     cin>>a;
     cout<<"Nilai r      : ";
     cin>>r;
     cout<<"Banyaknya deret : ";
     cin>>n;
     }

void geometri::proses(){
     bil[0]=a;
     bil[1]=a*r;
     int i=2;
     int x=1;
     while(i<n){
                for(int j=1;j<=i;j++){
                        x=x*r;
                        }
                bil[i] = a * x;
                x=1;
                i++;
                }
     }
    
void geometri::keluar(){
     cout<<"\nDeret Geometri:"<<endl;
     for(int y=0;y<n;y++){
             cout<<bil[y]<<" ";
             }
     cout<<endl<<endl;
     total=0;
     cout<<"Jumlah Deret : ";
     for(int y=0;y<n;y++){
             total=total+bil[y];
             }
     cout<<total<<"\n\n";
     }
int main(int argc, char *argv[])
{
    geometri jafar;
    jafar.masuk();
    jafar.proses();
    jafar.keluar();
   
    system("PAUSE");
    return EXIT_SUCCESS;
}