2=>10 digit system

int num=0, num1=0, r=0, i=0;
        Scanner in = new Scanner(System.in);
        System.out.println("Please enter the number:");
        num = in.nextInt();
        while(num > 0)
        {
            num1 = num%10;
            num /= 10;
            r += (int)(num1*Math.pow(2, i));
            i++;
        }
        System.out.print("Your number in 10-digit system is " + r);