Java addition with power of a number program wrong result

Question

In my program Logic is like:--

Input      Addition with      Output(result)
2            3                   5
3            3+4                10
4            3+4+4              15
5            3+4+4+4            20
6            3+4+4+4+4          25

So, I have made:--

import java.util.Scanner;

public class Addition {

           public static void main( String[] args) {
              @SuppressWarnings("resource")

            Scanner s = new Scanner(System.in);

              int result=0;

              System.out.print("Enter a number: ");

              int inputNumber = s.nextInt();

              if(inputNumber==2){
                  result = inputNumber+3; 

              }

              else{
                  Addition c=new Addition();


                      int j = inputNumber-2;

                      int power=c.pow(4,j);



                      result = inputNumber+3+power;


              }
              System.out.print(result);  

           }
          int pow(int c, int d)
             {       
                      int n=1;
                      for(int i=0;i<d;i++)
                      {
                               n=c*n;
                      }

                    return n;
             } 
}

In this program I am getting result:--

 Input               Output(result)
    2                        5
    3                       10
    4                       23
    5                       72

why? What Am I doing wrong??

Answer 1

You're confusing 'power of' with multiplication.

int power=c.pow(4,j);

should simply be:

int power= 4 * j;

Answer 2

You are calculating j correctly, its value will be 1 for inputNumber 3, 2 for inputNumber 4 and so on ...But You are not using it correctly. Note we are not adding powers of 4(4,16,64..), we are simply adding multiples of 4 in increasing order(4,8,12,..). So you should be adding 4*j to calculate the result

Change your code as follows:-

int j = inputNumber-2;

int multiple=4*j;

result = inputNumber+3+multiple;