Confused

If you want, you can break it down into pieces so that you will understand line by line.

int result = 0;
int i =1;

while(i != 6) {
    result = result + i;
    i++;
    System.out.println(result);
}

Do not use a separate class for the math operation. Your 'sum' class contains just a pass-through-method and makes the code unnecessarily complex. Write everything into the 'main' class!

I like my loop for (int i=1;i<=5;i++){ j=j+i; System.out.println(j);

I solved like this: package com.codegym.task.task03.task0309; /* Sum of 5 numbers */ public class Solution { public static void main(String[] args) { //write your code here int i; int a = 1; for (i = 1; i <= 5; i++) { System.out.println(a); a = a + (i + 1); } } }

public static void main(String[] args) { //write your code here int a=1; int b=1+2; int c=1+2+3; int d=1+2+3+4; int e=1+2+3+4+5; System.out.println(a); System.out.println(b); System.out.println(c); System.out.println(d); System.out.println(e); } simple as that

Try getting rid of the static variable and make it a local variable in the sum method. Generally it is bad practice to use static variables where there is no reason to. If this does not fix your validation problem then the problem might be bugged and won't allow verification. You don't necessarily need this but here is how you can write your method a little more compact:

public static void sum() {
   int s = 0;
   for (int i = 1; i <= 5; i++)
      System.out.println(s += i);
}