Need help in calculation 1+2+3+4...+n?

Question

So I'm assigned to write a program, which asks a number (n) and then makes a addition like this: 1+2+3+4...+n and prints the addition

I keep getting wrong numbers though and can't figure out what is wrong?

import java.util.Scanner;

public class LukusarjanSumma {

    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        int addition = 0;
        System.out.println("Where to?");
        int n = Integer.valueOf(reader.nextLine());
        while (addition <= n){
            addition += addition;
            addition ++;
        } System.out.println("Total is " + addition);
    }
}

Answer 1

You need to differenciate

• the additition that sums up all

• a counter that values the increasing index : 1,2,3...n

  int addition = 0;
  int counter = 0;
  System.out.println("Where to?");
  int n = Integer.parseInt(reader.nextLine());
  while (counter <= n) {
      addition += counter;
      counter++;
  }
  System.out.println("Total is " + addition);
  

But the easier would be to use a for loop, this is more logical

int n = Integer.parseInt(reader.nextLine());
for (int i = 0; i <= n; i++) {
    addition += i;
}