text: function checkType(number){
    if (typeof(number)==="number") {
  		return true
    }
    return false
  }
  
  let Calculator = {
      result: 0,
  add:  function (number=0){  
    if (checkType(number)) {
          Calculator.result = Calculator.result + number
    }
    return Calculator.add;
  },
  subtract: function (number=0) {
    if (checkType(number)) {
         Calculator.result = Calculator.result - number
     }
     return Calculator.subtract;
   },
   divide: function (number=1) {
     if (checkType(number)) {
         Calculator.result = Calculator.result / number
  	}
     return Calculator.divide;
  },
  multiply: function (number=1) {
     if (checkType(number)) {
      Calculator.result = Calculator.result * number
      }
     return Calculator.multiply;
  },   
  getResult: function () {
      return Calculator.result;
  },
  reset: function () {
       Calculator.result = 0;
    }  
  }
  
  module.exports=Calculator