text: let buttonSum = document.getElementById('sum');
  let buttonminus = document.getElementById('minus');
  let buttonmulti = document.getElementById('multi');
  let buttondivide = document.getElementById('divide');
  
  let input1 = document.getElementById('number_1');
  let input2 = document.getElementById('number_2');
  
  let answer = document.getElementById('answer');
  
  function getNumber1(){
      return Number(input1.value);
  }
  function getNumber2(){
      return Number(input2.value);
  }
  
  
  function makeOperation(operationCode){
  
      if (operationCode === '+') {
          var result = getNumber1() + getNumber2();  
          
      } else if (operationCode === '-') {
          var result = getNumber1() - getNumber2();
  
      } else if (operationCode === '*') {
          var result = getNumber1() * getNumber2();
  
      } else if (operationCode === '/') {
          var result = getNumber1() / getNumber2();
      } 
           
      document.getElementById('answer'). innerText = '=' + result;
  }
  
  function onButtonPlusCLick() {
      makeOperation('+'); 
  }
  
  function onButtonMimusCLick(){
      makeOperation('-'); 
  }
  function onButtonMultiCLick(){
      makeOperation('*'); 
  }
  function onButtonDivideCLick(){
      makeOperation('/'); 
  }
  
  buttonSum.addEventListener('click', onButtonPlusCLick);
  buttonminus.addEventListener('click', onButtonMimusCLick);
  buttonmulti.addEventListener('click', onButtonMultiCLick);
  buttondivide.addEventListener('click', onButtonDivideCLick);
  
  
  