how do i repeatedly multiply a number in java by 2 until it reaches 1 million?

Question

import java.util.Scanner;

class Main {

    static Scanner userInput = new Scanner(System.in);

    public static void main(String[] args) {
        int testNumber = userInput.nextInt();
        do{
             System.out.println(newNumber * 2);
             newNumber++;
        }while( testNumber < 1000000);
    }
}

Answer 1

You have the right idea with your loop, but you have multiple problems with your variables.

1. Your first problem is that you read in a variable from the user - testNumber, but then you are (incorrectly) manipulating a completely different variable - newNumber.
2. Your second problem is that you are testing the unchanged variable as your stop condition.

You probably want your loop to be something like:

    do {
         testNumber = testNumber * 2;
         System.out.println(testNumber);
    } while(testNumber < 1000000);