Is there a way to do this under all the same class? 

/*

The sum of all even numbers between 2 and 100 (inclusive).

The sum of all squares between 1 and 100 (inclusive)

All powers of 2 from 20 up to 220

The sum of all odd numbers between a and b (inclusive), where a and b are inputs

The sum of all odd digits of an input. (For example, if the input is 32677, the sum would be 3 + 7 + 7 = 17.)

*/

public class  E6_1

{

    public static void main(String[] args)

    {

    int sum=0;

        for(int i=1;i<=100;i++)

        {

            if(i%2==0)

            {

                System.out.println(i);

                sum+=i;

            }

        }

    System.out.println(sum);

    }

}

I did the first one, but I don't know if I can continue in this or have to open a new class. 

I don't want to open multiple classes and have to upload every single one individually but if theres no other way, then I'll settle