mult_button.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View view){
            Intent intent = new Intent(getBaseContext(), multiply_questions.class);
            sign = "1";
            intent.putExtra("SIGN", sign);
            startActivity(intent);
        }
    });

if(sign == "1") {
                question_mult.setText("What is " + num1 + " X " + num2 + "?");
            }
            else if(sign == "2"){
                question_mult.setText("What is " + num1 + " X " + num2 + "?");
            }
            else if(sign == "3"){
                question_mult.setText("What is " + num1 + " X " + num2 + "?");
            }
            else if(sign == "4"){
                question_mult.setText("What is " + num1 + " X " + num2 + "?");
            }else{
                question_mult.setText("Something went wrong! Blame Harry! See console for System.out.println()!");
                System.out.println("sign = " + sign);
            }